(#9051) Protect SQLite tests from running without gem.

In testing #9051 I introduced some tests that used the SQLite database adapter
to test StoreConfigs. Not everywhere that did so was protected correctly, so
machines without SQlite would blow up.

Now everything is guarded the way it should be, and tests no longer explode.

Signed-off-by: Daniel Pittman <daniel@puppetlabs.com>