[SUPPORT] Partial Update on Global Index with BLOOM_INDEX_UPDATE_PARTITION_PATH_ENABLE

**Describe the problem you faced**

Case 1.
We are currently trying to create a partial upsert pipeline with global index (GLOBAL_BLOOM). The issue that we face is that when setting HoodieIndexConfig.BLOOM_INDEX_UPDATE_PARTITION_PATH_ENABLE.key() -> "true", we notice that **the columns not updated by the partial update are dropped / nullified**.

Case 2.
In addition, as an alternative we are exploring using HoodieIndexConfig.BLOOM_INDEX_UPDATE_PARTITION_PATH_ENABLE.key() -> "false". However, in this case we notice that while the metadata column `_hoodie_partition_path` does not get updated, our partition field does.
In our unit testing, this means that for the record in question, the columns become `_hoodie_partition_path: partitionField=2022-05-07` and `partitionField: 2022-05-08`. We are wondering if there is any implications to this. For example, if there is any pruning in place on `_hoodie_partition_path`, is our record with mismatch in partition column info prone to any inconsistencies?

**To Reproduce**
Case 1.
Define
```
case class TestHudiTable(keyField: String, stringField: String, numberField: Int, precombineField: Timestamp, partitionField: Date)
val targetGlobalPartition = "2022-05-08"

val insertRecords = Seq(
TestHudiTable("key1", "value3", 55, Timestamp.valueOf("2022-05-07 08:00:00"), Date.valueOf("2022-05-07")),
TestHudiTable("key2", "value4", 66, Timestamp.valueOf("2022-05-07 09:00:00"), Date.valueOf("2022-05-07")),
TestHudiTable("key3", "value4", 77, Timestamp.valueOf("2022-05-07 10:00:00"), Date.valueOf("2022-05-07")))

val insertDF = insertRecords.toDF(keyField, stringField, numberField, precombineField, partitionField)
.withColumn(precombineField, col(precombineField).cast(TimestampType))
.withColumn(partitionField, to_date(col(partitionField)))
```
Then run an original insert of these records. Finally, test the partial upsert with the following records, using org.apache.hudi.common.model.OverwriteNonDefaultsWithLatestAvroPayload
```
val partialUpdates = Seq(
("key1", "value5", "2022-05-07T11:00:00", "2022-05-07"),
("key3", "value6", "2022-05-07T12:00:00", targetGlobalPartition)).toDF(
keyField, stringField, precombineField, partitionField).withColumn(
precombineField, col(precombineField).cast(TimestampType)).withColumn(
partitionField, to_date(col(partitionField)))
```

Hence, we are testing a partial update that updates most columns except numberField, which will be null.
```
**Before partial update to records corresponding to key1 and key3.**
+-------------------+---------------------+------------------+-------------------------+--------------------------------------------------------------------------+--------+-----------+-----------+-------------------+--------------+
|_hoodie_commit_time|_hoodie_commit_seqno |_hoodie_record_key|_hoodie_partition_path |_hoodie_file_name |keyField|stringField|numberField|precombineField |partitionField|
+-------------------+---------------------+------------------+-------------------------+--------------------------------------------------------------------------+--------+-----------+-----------+-------------------+--------------+
|20220622111807610 |20220622111807610_0_3|keyField:key1 |partitionField=2022-05-07|80700093-395f-4915-b39a-f97ba7527688-0_0-220-196_20220622111813282.parquet|key1 |value3 |55 |2022-05-07 08:00:00|2022-05-07 |
|20220622111807610 |20220622111807610_0_4|keyField:key3 |partitionField=2022-05-07|80700093-395f-4915-b39a-f97ba7527688-0_0-220-196_20220622111813282.parquet|key3 |value4 |77 |2022-05-07 10:00:00|2022-05-07 |
|20220622111813282 |20220622111813282_0_4|keyField:key2 |partitionField=2022-05-07|80700093-395f-4915-b39a-f97ba7527688-0_0-220-196_20220622111813282.parquet|key2 |value4 |66 |2022-05-07 09:00:00|2022-05-07 |
+-------------------+---------------------+------------------+-------------------------+--------------------------------------------------------------------------+--------+-----------+-----------+-------------------+--------------+

**After partial update to key1 and key3, with the latter also updating the partition column.**
+-------------------+---------------------+------------------+-------------------------+--------------------------------------------------------------------------+--------+-----------+-----------+-------------------+--------------+
|_hoodie_commit_time|_hoodie_commit_seqno |_hoodie_record_key|_hoodie_partition_path |_hoodie_file_name |keyField|stringField|numberField|precombineField |partitionField|
+-------------------+---------------------+------------------+-------------------------+--------------------------------------------------------------------------+--------+-----------+-----------+-------------------+--------------+
|20220622111818415 |20220622111818415_1_6|keyField:key3 |partitionField=2022-05-08|bce85553-9df0-4d02-a62c-0b2b81e58969-0_1-273-239_20220622111818415.parquet|key3 |value6 |null |2022-05-07 12:00:00|2022-05-08 |
|20220622111818415 |20220622111818415_0_5|keyField:key1 |partitionField=2022-05-07|80700093-395f-4915-b39a-f97ba7527688-0_0-273-238_20220622111818415.parquet|key1 |value5 |55 |2022-05-07 11:00:00|2022-05-07 |
|20220622111813282 |20220622111813282_0_4|keyField:key2 |partitionField=2022-05-07|80700093-395f-4915-b39a-f97ba7527688-0_0-273-238_20220622111818415.parquet|key2 |value4 |66 |2022-05-07 09:00:00|2022-05-07 |
+-------------------+---------------------+------------------+-------------------------+--------------------------------------------------------------------------+--------+-----------+-----------+-------------------+--------------+

```
We notice that the value for numberField is dropped upon the update.

Case 2.
For the second case, the setup and procedure is exactly the same, but we use instead HoodieIndexConfig.BLOOM_INDEX_UPDATE_PARTITION_PATH_ENABLE.key() -> "false".

All the fields are updated -- in particular, numberField is not dropped. However, we see the inconsistency across `partitionField` and `_hoodie_partition_path`. The results are shown below.

```
+-------------------+---------------------+------------------+-------------------------+--------------------------------------------------------------------------+--------+-----------+-----------+-------------------+--------------+
|_hoodie_commit_time|_hoodie_commit_seqno |_hoodie_record_key|_hoodie_partition_path |_hoodie_file_name |keyField|stringField|numberField|precombineField |partitionField|
+-------------------+---------------------+------------------+-------------------------+--------------------------------------------------------------------------+--------+-----------+-----------+-------------------+--------------+
|20220622114109089 |20220622114109089_0_3|keyField:key1 |partitionField=2022-05-07|3166a763-28e3-4352-a9a5-5403e2599bc5-0_0-220-196_20220622114117004.parquet|key1 |value3 |55 |2022-05-07 08:00:00|2022-05-07 |
|20220622114109089 |20220622114109089_0_4|keyField:key3 |partitionField=2022-05-07|3166a763-28e3-4352-a9a5-5403e2599bc5-0_0-220-196_20220622114117004.parquet|key3 |value4 |77 |2022-05-07 10:00:00|2022-05-07 |
|20220622114117004 |20220622114117004_0_4|keyField:key2 |partitionField=2022-05-07|3166a763-28e3-4352-a9a5-5403e2599bc5-0_0-220-196_20220622114117004.parquet|key2 |value4 |66 |2022-05-07 09:00:00|2022-05-07 |
+-------------------+---------------------+------------------+-------------------------+--------------------------------------------------------------------------+--------+-----------+-----------+-------------------+--------------+

+-------------------+---------------------+------------------+-------------------------+--------------------------------------------------------------------------+--------+-----------+-----------+-------------------+--------------+
|_hoodie_commit_time|_hoodie_commit_seqno |_hoodie_record_key|_hoodie_partition_path |_hoodie_file_name |keyField|stringField|numberField|precombineField |partitionField|
+-------------------+---------------------+------------------+-------------------------+--------------------------------------------------------------------------+--------+-----------+-----------+-------------------+--------------+
|20220622114126357 |20220622114126357_0_5|keyField:key1 |partitionField=2022-05-07|3166a763-28e3-4352-a9a5-5403e2599bc5-0_0-273-237_20220622114126357.parquet|key1 |value5 |55 |2022-05-07 11:00:00|2022-05-07 |
|20220622114126357 |20220622114126357_0_6|keyField:key3 |partitionField=2022-05-07|3166a763-28e3-4352-a9a5-5403e2599bc5-0_0-273-237_20220622114126357.parquet|key3 |value6 |77 |2022-05-07 12:00:00|2022-05-08 |
|20220622114117004 |20220622114117004_0_4|keyField:key2 |partitionField=2022-05-07|3166a763-28e3-4352-a9a5-5403e2599bc5-0_0-273-237_20220622114126357.parquet|key2 |value4 |66 |2022-05-07 09:00:00|2022-05-07 |
+-------------------+---------------------+------------------+-------------------------+--------------------------------------------------------------------------+--------+-----------+-----------+-------------------+--------------+

```

**Expected behavior**

Case 1.
In the first case, the hope is that the partial update any columns which are not null on the incremental load, and that any columns which are null in the incremental load but not null in hdfs are not nullified (numberField is nullified this case.

Case 2.
In this case, we want to confirm that this is expected behavior. In particular, we did not expect `partitionField` to be updated so it would remain consistent with `_hoodie_partition_path`. If this is indeed expected behavior, we would like to know how this may affect any pruning on reads from the dataset based on the partition column.

Currently, we see that a read filtered on `partitionField` is showing the updated record, but are unsure if there is any other pruning which instead uses `_hoodie_partition_path` on the backend, and which we should be aware of

```
readGlobalDataset().where(col(partitionField) === targetGlobalPartition).show(false)
+-------------------+---------------------+------------------+-------------------------+--------------------------------------------------------------------------+--------+-----------+-----------+-------------------+--------------+
|_hoodie_commit_time|_hoodie_commit_seqno |_hoodie_record_key|_hoodie_partition_path |_hoodie_file_name |keyField|stringField|numberField|precombineField |partitionField|
+-------------------+---------------------+------------------+-------------------------+--------------------------------------------------------------------------+--------+-----------+-----------+-------------------+--------------+
|20220622100847473 |20220622100847473_0_6|keyField:key3 |partitionField=2022-05-07|1f801a9d-5284-4e89-be48-c64273a4af79-0_0-273-237_20220622100847473.parquet|key3 |value6 |77 |2022-05-07 12:00:00|2022-05-08 |
+-------------------+---------------------+------------------+-------------------------+--------------------------------------------------------------------------+--------+-----------+-----------+-------------------+--------------+
```

**Environment Description**

* Hudi version : 0.11.0

* Spark version : 2.4.8

* Hive version : 2.3.7

* Hadoop version : 2.10.1

* Storage (HDFS/S3/GCS..) : GCS

* Running on Docker? (yes/no) : No, running on Dataproc 1.5

Start with HoodieIndexConfig.BLOOM_INDEX_UPDATE_PARTITION_PATH_ENABLE, the GLOBAL_BLOOM index path, and OverwriteNonDefaultsWithLatestAvroPayload, using the Scala/Spark reproduction in the issue. Compare both configuration values against the reported partial-upsert results. Done means the handling of null fields and the relationship between partitionField and _hoodie_partition_path are explained or corrected, with regression coverage for both cases.

Written by the indexing model from the issue text.