Ensure nullable partitioning column is handled properly

[fgwang7w]

== RELEASE NOTE ==

Hive changes
* Fix dynamic pruning failures for joining on null keys in hive partition

[fgwang7w]

resolve #15446

[kewang1024]

1. Can you merge those two commits into one commit?
2. Is it to solve a general issue or just for dynamic filtering?
3. Can you add integration test as well? (Example like:TestHiveDistributedJoinQueriesWithDynamicFiltering, TestHiveDistributedJoinQueriesWithDynamicFilteringAndFilterPushdown )

[fgwang7w]

1. Can you merge those two commits into one commit?
2. Is it to solve a general issue or just for dynamic filtering?
3. Can you add integration test as well? (Example like:TestHiveDistributedJoinQueriesWithDynamicFiltering, TestHiveDistributedJoinQueriesWithDynamicFilteringAndFilterPushdown )

Thanks for reviewing the PR.

1. done
2. this issue happends when dynamic filtering is on, so the fix is to solve for DF only
3. TestHiveDistributedJoinQueriesWithDynamicFiltering.testJoinOnNullPartitioning is added for integration test.

[fgwang7w]

@kewang1024 could you please help review the code? it'd be ideal if the code can be merged in the upcoming release, thanks

[fgwang7w]

hi@highker could you please merge this fix? I'm running some benchmark testing with DF on and this is blocking in many tcs, thx

[kewang1024]

1.For release note, it's not a general change, only hive change.
remove == NO RELEASE NOTE ==
2.Change the commit and release message to something like:
Fix dynamic pruning for null keys in hive partition

[kewang1024]

Also the release note please.
@highker can you help review this PR as well?