drainer: fix filter skip checkpoint problem

[lichunzhu]

What problem does this PR solve?

1. When pump continuously writes binlogs, it won't write any fake binlog
2. When drainer filters dml/ddl binlogs, it won't update checkpoint using filtered binlog's commit_ts.

If we continuously write TiDB but filter most tables, drainer's checkpoint tso won't update in a long time has some bad effects:

1. make users think drainer is stuck
2. triggers drainer checkpoint not change alert
3. waste time to recover from a much former checkpoint

What is changed and how it works?

Rewrite filtered binlogs to fake binlogs (commit ts = filtered binlog's commit ts) and send to drainer.
To avoid too many fake binlogs, we only re-generate fake binlogs after AT LEAST 3 SECONDS.

Check List

Tests

• Unit test
• Integration test

Code changes

• Has exported function/method change

Side effects

• Possible performance regression

Related changes

• Need to cherry-pick to the release branch

Release note

• No release note

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• amyangfei
• glorv

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[sre-bot]

No release note, Please follow https://github.com/pingcap/community/blob/master/contributors/release-note-checker.md

[lichunzhu]

/rebuild

[kennytm]

should this be cherry-picked to 4.0, 5.0, 5.1, 5.2?

[lichunzhu]

should this be cherry-picked to 4.0, 5.0, 5.1, 5.2?

Yes

[glorv]

/merge

[ti-chi-bot]

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

Commit hash: 547443f

[glorv]

/run-all-tests

[ti-chi-bot]

In response to a cherrypick label: new pull request created: #1073.

[ti-chi-bot]

In response to a cherrypick label: new pull request created: #1074.

[ti-chi-bot]

In response to a cherrypick label: new pull request created: #1075.

[ti-chi-bot]

In response to a cherrypick label: new pull request created: #1076.