Use ``re.search`` instead of ``re.match`` in sqlite

Use ``re.search`` instead of ``re.match`` in sqlite

Use python ``re.search()`` instead of ``re.match()`` as the operation
used by the :meth:`Column.regexp_match` method when using sqlite.
This matches the behavior of regular expressions on other databases
as well as that of well-known SQLite plugins.

Fixes: #5699
Change-Id: I14b2c7faf51fef172842aeb2dba2500f14544f24