Remove all platform-level dependencies

[di]

As a result of #18058, we don't need need these anymore.

The one exception is that we still need postgresql-client in our development containers to run various database-related commands.

Edit: we also need build-essential to provide make to our docs and dev builds.

[di]

Looks like this shaves about 30s off the Docker image build. 🚀

[miketheman]

This broke make totp by removing oathtool:

$ make totp
bin/devtotp: line 3: oathtool: command not found

make: *** [totp] Error 127

[miketheman]

Also looks like it broke make blog:

$ make blog
...
  File "/opt/warehouse/lib/python3.13/site-packages/git/__init__.py", line 298, in <module>
    raise ImportError("Failed to initialize: {0}".format(_exc)) from _exc
ImportError: Failed to initialize: Bad git executable.
The git executable must be specified in one of the following ways:
    - be included in your $PATH
    - be set via $GIT_PYTHON_GIT_EXECUTABLE
    - explicitly set via git.refresh(<full-path-to-git-executable>)

All git commands will error until this is rectified.

This initial message can be silenced or aggravated in the future by setting the
$GIT_PYTHON_REFRESH environment variable. Use one of the following values:
    - quiet|q|silence|s|silent|none|n|0: for no message or exception
    - warn|w|warning|log|l|1: for a warning message (logging level CRITICAL, displayed by default)
    - error|e|exception|raise|r|2: for a raised exception

Example:
    export GIT_PYTHON_REFRESH=quiet


make: *** [blog] Error 1

[ewdurbin]

#18252