executor: Refine partition number in hash join v2

[windtalker]

What problem does this PR solve?

Issue Number: ref #53127

Problem Summary: Current, we dispatch row to each partition by the LSB bits in hash value https://github.com/pingcap/tidb/blob/31c1de0b4f30d708de8228aa72c1a0dbff547504/pkg/executor/join/join_row_table.go#L540 And in each partition, we build hash table also based on the LSB bits in hash value https://github.com/pingcap/tidb/blob/31c1de0b4f30d708de8228aa72c1a0dbff547504/pkg/executor/join/hash_table_v2.go#L86 This may increase the hash table conflicts especially if partition number is power of 2

What changed and how does it work?

1. make the partition number to be a number that is pow of 2
2. dispatch row to each partition by the n MSB bits in hash value

Check List

Tests

• [x] Unit test
• [ ] Integration test
• [ ] Manual test (add detailed scripts or steps below)
• [ ] No need to test

  • [ ] I checked and no code files have been changed.

Side effects

• [ ] Performance regression: Consumes more CPU
• [ ] Performance regression: Consumes more Memory
• [ ] Breaking backward compatibility

Documentation

• [ ] Affects user behaviors
• [ ] Contains syntax changes
• [ ] Contains variable changes
• [ ] Contains experimental features
• [ ] Changes MySQL compatibility

Release note

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