MDEV-36397 Record change_user command in MTR output

[FarihaIS]

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Description

MTR .result files currently do not contain output to indicate if a change_user command has been executed in the corresponding .test files.

Record change_user command in the following format in MTR output only if enable_connect_log and enable_query_log is set to true: change_user <user>,<password>,<db>;

Release Notes

N/A

How can this PR be tested?

Execute the main suite in mysql-test-run. This commit modifies tests in that suite.

For example, a change_user root; line in the .test file will generate a new change_user root,,; line in the .result file if no password or db is set.

If a parameter (user, db, or password) is not specified, the current value for that parameter will be used in the output.

Basing the PR against the correct MariaDB version

• [x] This is a new feature and the PR is based against the latest MariaDB development branch.

Copyright

All new code of the whole pull request, including one or several files that are either new files or modified ones, are contributed under the BSD-new license. I am contributing on behalf of my employer Amazon Web Services, Inc.