Skip mjsunit/harmony/generators-turbo on arm64 debug sim

It seems to fail in nosnap mode, and runs very slowly with snapshot, so
skipping for now to get the tree green.

TBR=neis@chromium.org
BUG=v8:4907

Review URL: https://codereview.chromium.org/2000313002 .

Cr-Commit-Position: refs/heads/master@{#36452}

test/mjsunit/mjsunit.status

@@ -529,6 +529,9 @@
   # Issue 3219:
   'getters-on-elements': [PASS, ['gc_stress == True', FAIL]],
 
+  # BUG(v8:4907)
+  'harmony/generators-turbo': [SKIP],
+
   # Ignition.
   'es6/templates': [PASS, ['no_snap and mode == debug', NO_IGNITION]],
   'harmony/generators': [PASS, ['no_snap and mode == debug', NO_IGNITION]],