ChangeTagsTest: Mark tables as "used" to avoid ID reuse

ChangeTagsTest: Mark tables as "used" to avoid ID reuse

If ChangeTags::updateTags() isn't passed all three of $rc_id, $rev_id,
and $log_id, it attempts to look up proper values from the subset that
is passed.

Some of the tests in ChangeTagsTest blindly use certain IDs, expecting
them to either not exist in the relevant tables or at least to be sane
(e.g. the same log_id isn't used on multiple rc_id rows). Depending on
the exact behavior of previous tests, this expectation may not hold.

The simple fix is to just mark the relevant tables as "used" by
ChangeTagsTest so MediaWikiTestCase will truncate them.

Change-Id: Ie60092b8a6e50f6f8a5cfdaaf4cac8ddb4fc6f53