Yes, this is configurable through Makefile.PL resp. the META.json file in the distribution.
Most likely, the respective metainformation in these distributions is incomplete, but I don't see why the link for HTTP, which lives in the mod_perl distribution should go anywhere other than the mod_perl distribution.
When I visit the metacpan page for DB, it points to https://rt.perl.org/, (not http://rt.cpan.org), which is the correct link, because DB.pm is the Perl debugger, which is distributed with Perl itself and where Perl is upstream.