Add DatabaseUpdater::modifyTable

Add DatabaseUpdater::modifyTable

This introduces the function modifyTable to the DatabaseUpdater class
which will allow to alter multiple columns on the same table in a single
sql patch file. In favor of this new function, usage of
MssqlUpdater::updateSchema for mssql patches is discouraged for the
future.

Also fix T70786, which is about update rows being inserted regardless
whether applying the patch was successful or not (no retry on failure).
Now update rows only get inserted if applying the patch was successful.

Bug: T70786
Change-Id: Id2a1583cd9efa5ef271ae67238119bc24b76a3c6