Remove local-metric indexes for Autofill.FieldTypeValidation:ActualType.

We still have ...:PredictedType for testing.

Change-Id: I3d93a3f52d43b4aba408be336b93b1d01a385f16
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1825303Reviewed-by: Jesse Doherty <jwd@chromium.org>
Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Auto-Submit: Jesse Doherty <jwd@chromium.org>
Commit-Queue: Robert Kaplow <rkaplow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#700252}

tools/metrics/ukm/ukm.xml

@@ -1018,8 +1018,6 @@ be describing additional metrics about the same event.
     </summary>
     <aggregation>
       <history>
-        <index fields="metrics.PredictedType"/>
-        <index fields="metrics.PredictedType,metrics.PredictionSource"/>
         <statistics>
           <enumeration/>
         </statistics>