Remove the ktfmt.py hook from platform_testing/

This CL removes the hook using the (now deleted) ktfmt.py script. I
forgot to remove it in ag/27577577.

Bug: 342153000
Test: N/A
Flag: NONE Repohook Update
Change-Id: I97ac807a52623a5d4a1b94738f1c713299f7c6a3
1 file changed