fix: Fix predicates for base file reader in Flink FileGroup reader

[cshuo]

Describe the issue this Pull Request addresses

Fix issue: #14196

Summary and Changelog

The current pushed-down predicate for base file reader in flink FileGroup reader can be wrong in some cases, like

// base file: (uuid:'k1', age: 23, ts: 1003)
// log file: (uuid: 'k1', age: 25, ts: 1001)
// query filter: age = 25;
// Then the expected result should be empty, but if predicate age = 25 is pushed down
// into the parquet reader, the result would be wrong as (uuid: 'k1', age: 25, ts: 1001)

When there is log files in a file slice to merge during reading, we should make sure the predicate contains only record key fields.

Impact

Bug fix.

Risk Level

low

Documentation Update

Contributor's checklist

• Read through contributor's guide
• Enough context is provided in the sections above
• Adequate tests were added if applicable

[hudi-bot]

CI report:

• b242fb1 Azure: SUCCESS

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