This is an automated cherry-pick of #39936

What problem does this PR solve?

Issue Number: close #39929

Problem Summary:

The problem is that a pessimistic txn never locks a non-unique index key, and then the DDL merge worker only writes to the index key. These two txns are not aware of each other. For details, see #39929.

What is changed and how it works?

• Lock the row keys when merging back from the temp index.
• Add the temp index value format:
  • [delete_flag] [handle] [temp_key_ver]
  • [normal_flag] [origin_index_value] [temp_key_ver]
• Add a unit test for temp index value codec and a integration test for key locking.

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

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

Please refer to Release Notes Language Style Guide to write a quality release note.

None