[globalopt] Cleanup placeInitializers.

[gottesmm]

This whole function is just really hard for me to read. I did two things to ease that:

1. I extracted a helper function called getHoistedApplyForInitializer. When I extracted the helper function, I also inverted a conditional to make the control flow easier to read and eliminate a level of indentation.
2. I inverted a condition to clarify control flow and allow for an early-exit + indentation level reduction.

[gottesmm]

@swift-ci smoke test and merge

[gottesmm]

Linux failure is in SourceKit.

[gottesmm]

@swift-ci smoke test linux platform

[gottesmm]

@swift-ci smoke test linux platform