chore: Using cache factory method

[john-bodley]

SUMMARY

Switching the cache manager to use the factory method which allows the cache to be used within blueprints et al. prior to being bound to the application. This approach is also a step in the preferred direction, i.e., away from the legacy configuration defined here.

BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF

TEST PLAN

CI.

ADDITIONAL INFORMATION

• Has associated issue:
• Changes UI
• Requires DB Migration.
• Confirm DB Migration upgrade and downgrade tested.
• Introduces new feature or API
• Removes existing feature or API

[john-bodley]

It's interesting that the

@property
def cache(self) -> Cache:
    return self._cache

method didn't barf from a MyPy perspective given that self._cache is actually Optional[Cache] per the definition on line 28.

[bkyryliuk]

nice cleanup!