Expected distinct numbers is not parsed correctly

In the bloom filter feature, when I pass the expected distinct numbers as below, I got null values instead of 1000 and 200.
```java

import org.apache.hadoop.conf.Configuration;

Configuration conf = new Configuration();

conf.set("parquet.bloom.filter.column.names", "content,line"); conf.set("parquet.bloom.filter.expected.ndv","1000,200");
```
 
The issue is coming from getting the system property of expected distinct numbers through [Long.getLong(expectedNDVs[i])|https://github.com/apache/parquet-mr/blob/a737141a571e3cb6cee2c252dc4406e26e6c1177/parquet-hadoop/src/main/java/org/apache/parquet/hadoop/ParquetOutputFormat.java#L251].

It's possible to fix it by parsing the string with Long.parseLong(expectedNDVs[i]).

**Reporter**: [Walid Gara](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=garawalid) / @garawalid
**Assignee**: [Walid Gara](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=garawalid) / @garawalid
#### PRs and other links:
- [GitHub Pull Request #753](https://github.com/apache/parquet-mr/pull/753)

_{**Note**: *This issue was originally created as [PARQUET-1787](https://issues.apache.org/jira/browse/PARQUET-1787). Please see the [migration documentation](https://issues.apache.org/jira/browse/PARQUET-2502) for further details.*}

Open parquet-hadoop/src/main/java/org/apache/parquet/hadoop/ParquetOutputFormat.java around line 251 and trace how parquet.bloom.filter.expected.ndv is read from the configuration. Reproduce the example with values 1000 and 200, then verify that the expected distinct numbers are retained instead of becoming null.

Written by the indexing model from the issue text.