Feature proposal

• Firebase Component: APMAnalytics, GTMSessionUploadFetcher

I found [APMAnalytics load] and [GTMSessionUploadFetcher load] method take long time to execute, in my case, when app launches, [APMAnalytics load] takes 51ms and [GTMSessionUploadFetcher load] takes 95ms. see the pic below. I wish you can remove +load method considering Apple is not recommend +load.
By the way, there were too many +load method in firebase and related sdk, such as #6902 #6855 , I wonder if it is possible remove all +load to keep code in control