no issue
The `config` service has been a source of confusion when writing with modern Ember patterns because it's use of the deprecated `ProxyMixin` forced all property access/setting to go via `.get()` and `.set()` whereas the rest of the system has mostly (there are a few other uses of ProxyObjects remaining) eliminated the use of the non-native get/set methods.
- removed use of `ProxyMixin` in the `config` service by grabbing the API response after fetching and using `Object.defineProperty()` to add native getters/setters that pass through to a tracked object holding the API response data. Ember's autotracking automatically works across the native getters/setters so we can then use the service as if it was any other native object
- updated all code to use `config.{attrName}` directly for getting/setting instead of `.get()` and `.set()`
- removed unnecessary async around `config.availableTimezones` which wasn't making any async calls
no issue
- without this there's no indication the config flag is set when you have no access to the config file or you don't know which features are currently behind the flag
