[ARCMigrate] When applying changes from remap files, disable the...

[ARCMigrate] When applying changes from remap files, disable the 'adjustRemovals' functionality of EditedSource

'adjustRemovals' is used to avoid situation when removing a range inadvertently causes 2 separate identifiers to get joined into one.
But it is not useful when the edits are character precise, as is the case with the remap files.

llvm-svn: 301602