Reverts: flutter/flutter#152049
Initiated by: cbracken
Reason for reverting: iOS builds failing in post-submit
Original PR Author: loic-sharma
Reviewed By: {jmagman}
This change reverts the following previous change:
Changes:
1. Enables Swift Package Manager by default on the main/master channel
2. Fixes tests that fail if Swift Package Manager is enabled
Corresponding docs change: https://github.com/flutter/website/pull/10938
Addresses https://github.com/flutter/flutter/issues/151567
f55ab0e77e