Reverts "chore: turn on waitOnContentHash flag (#4714)" (#4717)

Reverts: #4714
Initiated by: matanlurey
Reason for reverting: Not working as expected.
Original PR Author: jtmcdole

Reviewed By: {matanlurey}

This change reverts the following previous change:
Round 2: roll-forward after a new build that supports this.

Author: auto-submit[bot]

app_dart/config.yaml

@@ -4,8 +4,3 @@
 # app_dart/lib/src/service/config.dart
 
 backfillerCommitLimit: 50
-
-contentAwareHashing:
-  # This will cause PRs that enter the merge queue to wait on CAH hashing
-  # to happen before scheduling builds.
-  waitOnContentHash: true