Refreshing the environment should refresh the cached plans

[tpoliaw]

In a repl with a blueapi client

>>> bc = BlueapiClient.from_config_file('tests/system_tests/config.yaml').with_instrument_session("cm12345-1")
>>> bc.plans.missing
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/dls/athena/blueapi/src/blueapi/client/client.py", line 97, in __getattr__
    raise AttributeError(f"No plan named '{name}' available")
AttributeError: No plan named 'missing' available
>>> # Add a 'missing' plan to a module included in the server
>>> bc.reload_environment()
EnvironmentResponse(environment_id=UUID('72aabe8e-1fdd-4f52-a23d-5717a2ccb725'), initialized=True, error_message=None)
>>> bc.plans.missing
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/dls/athena/blueapi/src/blueapi/client/client.py", line 97, in __getattr__
    raise AttributeError(f"No plan named '{name}' available")
AttributeError: No plan named 'missing' available

After the reload, the cached plans should be refreshed to ensure new plans are available and removed plans don't linger.