[SUPPORT] Does Hudi re-create record level index during an upsert operation?

**Describe the problem you faced**

I created a hudi table with record level index and performed upsert operation on it. Now, the first time when I performed the upsert operation, it read the record index file, figured out which files needed an update, and wrote the files to S3. The second time when I performed an upsert on the same table, I saw the record index folder being deleted and recreated under the metadata folder. My hudi table is quite large and this re-creation of the entire record level index is too expensive to support during an upsert operation.

**To Reproduce**

Steps to reproduce the behavior:

1. Create hudi table using insert mode and specify record level index
2. Perform an upsert
3. Perform another upsert

**Expected behavior**

I expect any number of upserts after the initial creation of the record level index to just update the index as required and not re-create the whole index.

**Environment Description**

* Hudi version : 0.15.0

* Spark version : 3.4.1

* Hive version :

* Hadoop version : 3.3.6

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

* Running on Docker? (yes/no) : no

**Additional context**

Config I used for upsert operation:

```
hoodie.embed.timeline.server -> false,
hoodie.parquet.small.file.limit -> 1073741824,
hoodie.metadata.record.index.enable -> true,
hoodie.datasource.write.precombine.field -> $timestampField,
hoodie.datasource.write.payload.class -> org.apache.hudi.common.model.OverwriteWithLatestAvroPayload,
hoodie.metadata.index.column.stats.enable -> true,
hoodie.parquet.max.file.size -> 2147483648,
hoodie.metadata.enable -> true,
hoodie.index.type -> RECORD_INDEX,
hoodie.datasource.write.operation -> upsert,
hoodie.parquet.compression.codec -> snappy,
hoodie.datasource.write.recordkey.field -> $recordKeyField,
hoodie.table.name -> $tableName,
hoodie.datasource.write.table.type -> COPY_ON_WRITE,
hoodie.datasource.write.hive_style_partitioning -> true,
hoodie.write.markers.type -> DIRECT,
hoodie.populate.meta.fields -> true,
hoodie.datasource.write.keygenerator.class -> org.apache.hudi.keygen.SimpleKeyGenerator,
hoodie.upsert.shuffle.parallelism -> 10000,
hoodie.datasource.write.partitionpath.field -> $partitionField
```

I do not see any errors but it doesn't make sense that hudi will clear away my index and recreate it.

Start by reproducing the two-upsert sequence with Hudi 0.15.0, Spark 3.4.1, S3, and the listed record-index configuration. Inspect the metadata record-index folder after each upsert and determine whether full recreation is expected or indicates a bug. Done means the behavior is explained and, if incorrect, covered by a reproducible test or targeted fix.

Written by the indexing model from the issue text.