infoschema, executor, txn: change some field name in TIDB_TRX table

[longfangsong]

What problem does this PR solve?

Problem Summary:
Some field names in TIDB_TRX table are not very easy to understand.

What is changed and how it works?

What's Changed:

Change COUNT into MEM_BUFFER_KEYS and LEN into MEM_BUFFER_BYTES.

Check List

Tests

• No code

Release note

• No release note.

[longfangsong]

/cc @MyonKeminta

[longfangsong]

/cc @MyonKeminta

[ti-chi-bot]

@MyonKeminta: Thanks for your review. The bot only counts approvals from reviewers and higher roles in list, but you're still welcome to leave your comments.

In response to this:

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the ti-community-infra/tichi repository.

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• MyonKeminta
• youjiali1995

To complete the pull request process, please ask the reviewers in the list to review by filling /cc @reviewer in the comment.
After your PR has acquired the required number of LGTMs, you can assign this pull request to the committer in the list by filling /assign @committer in the comment to help you merge this pull request.

The full list of commands accepted by this bot can be found here.

Reviewer can indicate their review by submitting an approval review.
Reviewer can cancel approval by submitting a request changes review.

[youjiali1995]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: a901ed8

[MyonKeminta]

/merge

[MyonKeminta]

/merge

[MyonKeminta]

/merge

[MyonKeminta]

/merge

[Rustin170506]

/merge

@MyonKeminta You don't need to /merge as often, and if a test fails, you only need to run the test that failed. The bot will automatically merge PRs when all tests pass. there is no need to use /merge to trigger all tests.

[MyonKeminta]

/run-integration-common-test

[ti-chi-bot]

@longfangsong: Your PR was out of date, I have automatically updated it for you.

At the same time I will also trigger all tests for you:

/run-all-tests

If the CI test fails, you just re-trigger the test that failed and the bot will merge the PR for you after the CI passes.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the ti-community-infra/tichi repository.