feat: fix regression test, add a new CI workflow

[airween]

what

This PR fixes the last broken regression test and adds the whole regression test workflow to GH CI.

why

The regression tests were almost finished, now I found another broken test. After fixed that I prepared a new workflow for GH CI, where we run these regression tests.

I switched the operation system to Ubuntu 24.04 (from 22.04). In Ubuntu 24.04 the old PCRE (libpcre3) is not installed by default, I had to add it explicitly.

I tried to follow the build matrix as it's in other workflows, but a complete regression test takes about 29 minutes - I think that's very slow. On my build machine (which is not a strong one) it takes about 6-7 minutes.

Unfortunately we can't fix this, the reason is that the operation of a test: each tests creates a config, start an Apache server with that config, send a request and check the output (files, response, etc).

I don't know if it's worth it.

references

#3425

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[theseion]

I looked at run-regression-tests.pl.in quickly and it seems to me that match_log might be the issue. Log flushing can differ significantly between systems, so it's possible that searching the log in each test takes a long time. I suggest you add some debug print statements to the Perl script so that you can see in the CI output which operations use a lot of time.