Remove backend warnings from SSL tests

When looking at a patch in the CFBot I realized that the SSL tests generate
backend warnings under ENFORCE_REGRESSION_TEST_NAME_RESTRICTIONS due to roles
and databases not following the regression test naming convention. While not
impacting the tested functionality, it's pretty silly to have warnings in the
test logs which can be avoided since those can throw off users debugging a test
failure.

The attached renames all roles with a regress_ prefix and databases with a
regression_ prefix to match the convention, and regenerates the certificates to
match. With this I get a clean warning-free testrun. There are no functional
changes included, just changed names (and comments to match).

--
Daniel Gustafsson