[BUG] Traceback when cassandra python libraries are unavailable

[garethgreenaway]

Description
when the cassandra python library is unavailable the following traceback is shown when running some Salt commands.

[ERROR   ] Failed to import module cassandra_cql, this is due most likely to a syntax error:
Traceback (most recent call last):
  File "/home/gareth/code/salt/salt/loader/lazy.py", line 768, in _load_module
    mod = self.run(spec.loader.load_module)
  File "/home/gareth/code/salt/salt/loader/lazy.py", line 1228, in run
    return self._last_context.run(self._run_as, _func_or_method, *args, **kwargs)
  File "/home/gareth/code/salt/salt/loader/lazy.py", line 1243, in _run_as
    return _func_or_method(*args, **kwargs)
  File "<frozen importlib._bootstrap_external>", line 407, in _check_name_wrapper
  File "<frozen importlib._bootstrap_external>", line 907, in load_module
  File "<frozen importlib._bootstrap_external>", line 732, in load_module
  File "<frozen importlib._bootstrap>", line 265, in _load_module_shim
  File "<frozen importlib._bootstrap>", line 696, in _load
  File "<frozen importlib._bootstrap>", line 677, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 728, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "/home/gareth/code/salt/salt/modules/cassandra_cql.py", line 144, in <module>
    "HostDistance": HostDistance,
NameError: name 'HostDistance' is not defined

Versions Report

salt --versions-report

(Provided by running salt --versions-report. Please also mention any differences in master/minion versions.)

Salt Version:
          Salt: 3005.1+683.g1404abe773
 
Dependency Versions:
          cffi: Not Installed
      cherrypy: Not Installed
      dateutil: Not Installed
     docker-py: Not Installed
         gitdb: Not Installed
     gitpython: Not Installed
        Jinja2: 3.1.2
       libgit2: Not Installed
      M2Crypto: Not Installed
          Mako: Not Installed
       msgpack: 1.0.4
  msgpack-pure: Not Installed
  mysql-python: Not Installed
     pycparser: Not Installed
      pycrypto: Not Installed
  pycryptodome: 3.15.0
        pygit2: Not Installed
        Python: 3.7.7 (default, Sep  4 2020, 16:48:08)
  python-gnupg: Not Installed
        PyYAML: 6.0
         PyZMQ: 20.0.0
         smmap: Not Installed
       timelib: Not Installed
       Tornado: 4.5.3
           ZMQ: 4.3.3
 
System Versions:
          dist: manjaro 22.0.0 Sikaris
        locale: UTF-8
       machine: x86_64
       release: 5.17.15-1-MANJARO
        system: Linux
       version: Manjaro Linux 22.0.0 Sikaris

Additional context
Add any other context about the problem here.