Revert "Remove unused 'dsn' function and its usage"

[Martchus]

Reverts #4928 as it is actually used in production, e.g. o3

[Martchus]

Note that the error message was:

Aug 01 13:57:08 ariel systemd[1]: Started The openQA web UI.
Aug 01 13:57:09 ariel openqa-webui-daemon[11005]: Can't connect to data source 'HASH(0x55d82c060598)' because I can't work out what driver to use (it doesn't seem to contain a 'dbi:driver:' prefix and the DBI_DRIVER env var is not set)>
Aug 01 13:57:09 ariel systemd[1]: openqa-webui.service: Main process exited, code=exited, status=255/EXCEPTION
Aug 01 13:57:09 ariel systemd[1]: openqa-webui.service: Failed with result 'exit-code'.

And it didn't help to simply remove the line user = geekotest from database.ini. I can also reproduce the problem locally by starting openQA as usual with a database.ini that is identical to the default.

[codecov]

Codecov Report

Attention: Patch coverage is 28.57143% with 5 lines in your changes missing coverage. Please review.

Project coverage is 98.49%. Comparing base (6e1262d) to head (b34ad05).

Files	Patch %	Lines
lib/OpenQA/Shared/Plugin/Gru.pm	40.00%	3 Missing ⚠️
lib/OpenQA/Schema.pm	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5813      +/-   ##
==========================================
- Coverage   98.50%   98.49%   -0.02%     
==========================================
  Files         394      394              
  Lines       38678    38683       +5     
==========================================
  Hits        38099    38099              
- Misses        579      584       +5     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[baierjan]

And of course, now the issue is in our docker compose tests:

webui-db-init-1  | Can't connect to data source 'HASH(0x563a5c882088)' because I can't work out what driver to use (it doesn't seem to contain a 'dbi:driver:' prefix and the DBI_DRIVER env var is not set) at /usr/lib/perl5/vendor_perl/5.26.1/Mojo/Pg.pm line 73.