*: fix regression from FLUSH PRIVILEGES fix

[morgo]

What problem does this PR solve?

Issue Number: close #28559

Problem Summary:

The 3 tests failed because of the first failure in the role test, and then a failure to cleanup after the first failure.

The root cause is an uncaught error, which is a regression introduced in #27958

This also removes "FLUSH PRIVILEGES" from tests where it is not required. This is done to prevent future regressions, since GRANT is expected to reload the privilege tables.

An incorrect error message is also fixed.

What is changed and how it works?

What's Changed:

A recently introduced regression is fixed (set default role for current user does not validate roles exist.)

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

No release note because the bug was introduced and fixed before a user release.

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• tiancaiamao
• xhebox

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[morgo]

/run-check_dev_2

[tiancaiamao]

/merge

[ti-chi-bot]

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

Commit hash: a3dfca7

[tiancaiamao]

/merge

[ti-chi-bot]

@morgo: Your PR was out of date, I have automatically updated it for you.

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/run-all-tests

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