fix(database_observability.postgres): Correctly handle dsn with unix sockets

[k3-cat]

Brief description of Pull Request

Fixes dsnParseRegex so that replaceDatabaseNameInDSN can properly handle dsn with unix sockets, instead of treating the final part of sockets path as dbname.

Pull Request Details

Current behaviour

• Thus, alloy will try to connect /run/{dbname}/.s.PGSQL.5432 and produce error: dial unix /run/{dbname}/.s.PGSQL.5432: connect: no such file or directory

Fixed behaviour

Although simply replace the .+ in matching group 1 with .*? or [^?]* can solve this issue as well, the current approach provides better robustness for future changes and edge cases (eg. unescaped spaces present in dsn).

Issue(s) fixed by this Pull Request

nil

Notes to the Reviewer

• matching group 3 is also rewired for better readability (as .* would match \?? anyway) and robustness under edge cases
• $ in matching group 3 is dropped intentionally, as this can generally improve the performance sightly

PR Checklist

• Documentation added (maybe not applicable?)
• Tests updated
• Config converters updated (not applicable)

[cla-assistant]

All committers have signed the CLA.