Bug 11701: (follow-up) move unit tests to t/db_dependent

Bug 11701: (follow-up) move unit tests to t/db_dependent

The new tests will not function if there isn't a valid
configuration (or mocking of preference()) so this patch
moves them to t/db_dependent/Context.t.

To test:

[1] After applying the main patch for this bug, verify that
    prove -v t/db_dependent/Context.t passes.

Signed-off-by: Galen Charlton <gmc@esilibrary.com>
(cherry picked from commit 8205529683da0f934f4bdb26ccd54f05b8246d0a)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>
Conflicts:
	t/Context.t