Addresses ENG-1938. Learned more about this issue here.
This diff effectively reverts D30. Back then, the default was ENABLE_BITCODE = YES, and that diff had the effect of disabling bitcode for debug builds. Now that ENABLE_BITCODE = NO is the default, that diff has the effect of enabling bitcode for release builds.
Deleting these lines puts us back to "default" behavior, which is now to have bitcode disabled.