Fix a bug in the releasetools common.py script.

The script was not breaking out of the loop when a handler was found, which could lead to multiple handlers being called for the same option.

This fixes the issue that a single option can be handled in two handlers.

Bug: 345402175
Test: sign_target_files_apks -k ..
Change-Id: I9f4ef801df99a4a0f2ba5be994b3f37fbedc22c0