Drop less used Horizon plugins

[cityofships]

This arguably speeds up container image builds and potentially reduces attack surface. Could help with dependecies install issues especially in EOL releases as well.

Allows installations from custom sources via horizon-plugin-* path e.g. for Cloudkitty.

freezer, mistral, murano, sahara, senlin, solum, tacker, trove, vitrage, watcher and zun plugins are removed.

[mnasiadka]

Very arguably, they will still be downloaded by kolla-build - what's the speed and size gain?

[cityofships]

Very arguably, they will still be downloaded by kolla-build - what's the speed and size gain?

I haven't measured that. The main motivation in fact is/was to avoid dependency issues like this:

INFO:kolla.common.utils.horizon:Collecting XStatic-Moment-Timezone>=0.5.22.0 (from vitrage-dashboard==4.0.0.0rc2.dev2)
INFO:kolla.common.utils.horizon:  Downloading XStatic-Moment-Timezone-0.5.22.0.tar.gz (99 kB)
INFO:kolla.common.utils.horizon:  Installing build dependencies: started
INFO:kolla.common.utils.horizon:  Installing build dependencies: finished with status 'done'
INFO:kolla.common.utils.horizon:  Getting requirements to build wheel: started
INFO:kolla.common.utils.horizon:  Getting requirements to build wheel: finished with status 'error'
INFO:kolla.common.utils.horizon:ESC[91m  error: subprocess-exited-with-error
INFO:kolla.common.utils.horizon:
INFO:kolla.common.utils.horizon:  × Getting requirements to build wheel did not run successfully.
INFO:kolla.common.utils.horizon:  │ exit code: 1
INFO:kolla.common.utils.horizon:  ╰─> [19 lines of output]
INFO:kolla.common.utils.horizon:      /tmp/pip-build-env-0hh9olqy/overlay/lib/python3.9/site-packages/_distutils_hack/__init__.py:53: UserWarning: Reliance on distutils from stdlib is deprecated. Users must rely on setuptools to provide the distutils
 module. Avoid importing distutils or import setuptools first, and avoid setting SETUPTOOLS_USE_DISTUTILS=stdlib. Register concerns at https://github.com/pypa/setuptools/issues/new?template=distutils-deprecation.yml
INFO:kolla.common.utils.horizon:        warnings.warn(
INFO:kolla.common.utils.horizon:      Traceback (most recent call last):
INFO:kolla.common.utils.horizon:        File "/var/lib/kolla/venv/lib64/python3.9/site-packages/pip/_vendor/pyproject_hooks/_in_process/_in_process.py", line 389, in <module>
INFO:kolla.common.utils.horizon:          main()
INFO:kolla.common.utils.horizon:        File "/var/lib/kolla/venv/lib64/python3.9/site-packages/pip/_vendor/pyproject_hooks/_in_process/_in_process.py", line 373, in main
INFO:kolla.common.utils.horizon:          json_out["return_val"] = hook(**hook_input["kwargs"])
INFO:kolla.common.utils.horizon:        File "/var/lib/kolla/venv/lib64/python3.9/site-packages/pip/_vendor/pyproject_hooks/_in_process/_in_process.py", line 143, in get_requires_for_build_wheel
INFO:kolla.common.utils.horizon:          return hook(config_settings)
INFO:kolla.common.utils.horizon:        File "/tmp/pip-build-env-0hh9olqy/overlay/lib/python3.9/site-packages/setuptools/build_meta.py", line 331, in get_requires_for_build_wheel
INFO:kolla.common.utils.horizon:          return self._get_build_requires(config_settings, requirements=[])
INFO:kolla.common.utils.horizon:        File "/tmp/pip-build-env-0hh9olqy/overlay/lib/python3.9/site-packages/setuptools/build_meta.py", line 301, in _get_build_requires
INFO:kolla.common.utils.horizon:          self.run_setup()
INFO:kolla.common.utils.horizon:        File "/tmp/pip-build-env-0hh9olqy/overlay/lib/python3.9/site-packages/setuptools/build_meta.py", line 512, in run_setup
INFO:kolla.common.utils.horizon:          super().run_setup(setup_script=setup_script)
INFO:kolla.common.utils.horizon:        File "/tmp/pip-build-env-0hh9olqy/overlay/lib/python3.9/site-packages/setuptools/build_meta.py", line 317, in run_setup
INFO:kolla.common.utils.horizon:          exec(code, locals())
INFO:kolla.common.utils.horizon:        File "<string>", line 2, in <module>
INFO:kolla.common.utils.horizon:      ImportError: cannot import name 'moment_timezone' from 'xstatic.pkg' (unknown location)
INFO:kolla.common.utils.horizon:      [end of output]
INFO:kolla.common.utils.horizon:
INFO:kolla.common.utils.horizon:  note: This error originates from a subprocess, and is likely not a problem with pip.
INFO:kolla.common.utils.horizon:ESC[0m
INFO:kolla.common.utils.horizon:ESC[91mERROR: Failed to build 'XStatic-Moment-Timezone' when getting requirements to build wheel
INFO:kolla.common.utils.horizon:ESC[0m