Do not validate deleted configs

This bug caused https://logs.chromium.org/logs/infra-internal/buildbucket/cr-buildbucket.appspot.com/8925230260185002096/+/steps/presubmit/0/stdout

Tested locally

R=vadimsh@chromium.org

Change-Id: I9c42b7d7e9a1366e00fe40ca8a9f18ff0629663a
Reviewed-on: https://chromium-review.googlesource.com/c/1396527
Auto-Submit: Nodir Turakulov <nodir@chromium.org>
Commit-Queue: Vadim Shtayura <vadimsh@chromium.org>
Reviewed-by: Vadim Shtayura <vadimsh@chromium.org>

presubmit_canned_checks.py

@@ -1312,7 +1312,7 @@ def CheckChangedLUCIConfigs(input_api, output_api):
     ('%s/' % cs['location']) == loc_pref
   }
   cs_to_files = collections.defaultdict(list)
-  for f in input_api.AffectedFiles():
+  for f in input_api.AffectedFiles(include_deletes=False):
     # windows
     file_path = f.LocalPath().replace(_os.sep, '/')
     logging.debug('Affected file path: %s', file_path)