Ensure git tag tests and others create test repos in tmpdir (#18447) (#18767)

Ensure git tag tests and others create test repos in tmpdir (#18447) (#18767)

Backport #18447

* Ensure git tag tests and other create test repos in tmpdir

There are a few places where tests appear to reuse testing repos which
causes random CI failures.

This PR simply changes these tests to ensure that cloning always happens
into new temporary directories.

Fix #18444

* Change log root for integration tests to use the REPO_TEST_DIR

There is a potential race in the drone integration tests whereby test-mysql etc
will start writing to log files causing make test-check fail.

Fix #18077

Signed-off-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: 6543 <6543@obermui.de>