chore(rel): remove legacy scripts and update utils (#1125)

This PR removes some outdated an unmaintained scripts that were provided
to assist customers in setting up Sourcegraph via Docker Compose in
different environments.

From what we have seen, very few customers use these scripts. In
addition, users looking to install Docker Compose are likely best served
by following the official [Docker Compose
documentation](https://docs.docker.com/compose/install/), rather than
using potentially outdated scripts.

### Checklist

<!--
Kubernetes and Docker Compose MUST be kept in sync. You should not merge
a change here
without a corresponding change in the other repository, unless it truly
is specific to
this repository. If uneeded, add link or explanation of why it is not
needed here.
-->
* [NA] Sister
[deploy-sourcegraph](https://github.com/sourcegraph/deploy-sourcegraph)
change:
* [NA] Sister
[customer-replica](https://github.com/sourcegraph/deploy-sourcegraph-docker-customer-replica-1)
change (if necessary, for any changes affecting pure-docker or
configuration):
* [NA] All images have a valid tag and SHA256 sum
### Test plan

CI test pipeline

<!--
As part of SOC2/GN-104 and SOC2/GN-105 requirements, all pull requests
are REQUIRED to
provide a "test plan". A test plan is a loose explanation of what you
have done or
implemented to test this, as outlined in our Testing principles and
guidelines:

https://docs.sourcegraph.com/dev/background-information/testing_principles
  Write your test plan here after the "Test plan" header.
-->

Author: jdpleiness