*: remove more about tidb/parser/mysql

[xhebox]

What problem does this PR solve?

Issue Number: ref #248

Problem Summary: I hope there can be a single mysql package for mysql protocol parsing and serializing before we remove *PacketIO.

What is changed and how it works:

1. Use more pnet.Capbility
2. Use more pnet.AuthXX and pnet.XXXHeader

Check List

Tests

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

Notable changes

• Has configuration change
• Has HTTP API interfaces change
• Has tiproxyctl change
• Other user behavior changes

Release note

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

None

[purelind]

/test pull-mysql-connector-test

[xhebox]

/test pull-mysql-connector-test

[ti-chi-bot]

@xhebox: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
wip/pull-mysql-connector-test	bb924f4	link	true	/test pull-mysql-connector-test

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[xhebox]

/test pull-mysql-connector-test

[xhebox]

/test pull-mysql-connector-test

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: djshow832

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• OWNERS [djshow832]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2023-07-28 07:04:29.16318451 +0000 UTC m=+510811.757715498: ☑️ agreed by djshow832.