iOS - Implement feature flag parity for Segment-Firebase implementation

Currently, Android and iOS have a slight difference in how they utilize the Segment and Firebase configurations and enable/disable features based on it.

Current working:

1. Android checks if Segment is enabled and Firebase Analytics is also enabled then Segment's integration for Firebase is used

2. Whereas iOS checks if Segment is enabled and Firebase is configured properly (i.e. all Firebase keys are present in config) then Segment's integration for Firebase is used

Updated workflow:
We can achieve parity on both OS by changing the Firebase config as follows:

Acceptance Criteria

1. Both mobile platform teams should have consensus on this updated workflow

2. Feature flag wiki should be updated

3. Application codes will need to update as well