[test] Skip flaky test

TBR=jgruber@chromium.org
NOTRY=true

Bug: v8:7763
Change-Id: I908cb159d92df4f429ae77b6fa202da321583b36
Reviewed-on: https://chromium-review.googlesource.com/1064232Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53236}

test/cctest/cctest.status

@@ -218,6 +218,9 @@
   # support.
   'test-serialize/CustomSnapshotDataBlobWithWarmup': [SKIP],
   'test-serialize/SnapshotDataBlobWithWarmup': [SKIP],
+
+  # https://crbug.com/v8/7763
+  'test-lockers/ExtensionsRegistration': [SKIP],
 }],  # 'no_snap == True'
 ['no_snap == False', {
   # FunctionEntryHooks require bootstrapping from scratch.