fix: Don't explicitly use a socket for Postgres

[stahnma]

Previously, the default configuration for flox/postgres uses both a socket and
a TCP connection. This was both redundant and caused Postgres not to start in
several scenarios -- primarily because the postgres socket file path was deep
in the .flox structure, which already might be deep in the filesystem. The
maximum lenght for a file socket path on MacOS is 103 characters. If it's
longer than that, PG will not start. This change simply removes the call to -c socket because it's redundant with the way Postgres is already configured via
this env.

Additionally, the presence of PGHOST cause the primary go Postgres library to
panic as it tries to parse that even when the presence of TCP connection
information is available.

[rossturk]

I have made this change and reverted it once before.

It was a while ago, but IIRC it was because in my testing I encountered a super bare system where this did not work. It was then that I realized that most systems where I work had, at one time or another, had Postgres installed via a package manager with elevated privs. Once I tried it on a system that never had, it failed because (iirc) a required suidroot socket was missing.

[rossturk]

Please make sure this works across all of our footprints (including wsl and flox containerize) - I have tried this before and reverted after encountering issues.

Also, be good to check that this can still support multiple instances on the same host (configured with alternate ports).