[TASK] runTests.sh: Use sqlite by default for functionals

Change the default DBMS for functional tests in
runTests.sh from mariadb to sqlite: sqlite is
sigificantly quicker with functional tests and
thus the preferred DBMS selection when running
tests locally for us lazy devs since we can omit
the '-d sqlite' option now.

This has no impact on CI since the DBMS is
always explicitly set in gitlab-ci configs.

Resolves: #96585
Releases: main, 11.5
Change-Id: I93b68f48a409fc1afb14d8a2aecbc295dd2255e5
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/73113


Tested-by: core-ci <typo3@b13.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>