Decouple deletion of change edits from deletion of file in edit

I4706f565 introduced dedicated endpoint for deletion of change edits.
The combined logic in ChangeEdits.DeleteEdit can be now removed, the
endpoint can be renamed to match the new functionality and the code
can be simplified and adjusted to only one use case: deletion of files
in change edit.

Change-Id: I64fcb1557ead6e7bcdb75deb148a21d1d132cee4
2 files changed