privilege/privileges, server: stabalize tests

[morgo]

What problem does this PR solve?

Issue Number: close #33245

Problem Summary:

The server test tries to listen on port 4000 / 10080 which are the defaults. So if TiDB is running on the same system it will fail (seems pretty common this might be the case on a developer machine).

The privileges test has leaks. It might be related to the go 1.18 upgrade since nothing has changed.. but it could also be a race that is now common since I had previously seen these errors but they went away.

What is changed and how it works?

Fixed tests only.

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

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• hawkingrei
• ngaut

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[sre-bot]

Code Coverage Details: https://codecov.io/github/pingcap/tidb/commit/992ed6c5d4b15fd86482a596269cd3f51969168e

[ngaut]

/merge

[ti-chi-bot]

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

Commit hash: 21968fa

[hawkingrei]

/run-mysql-test

[ti-srebot]

cherry pick to release-5.4 in PR #33274

[ti-srebot]

cherry pick to release-6.0 in PR #33275