Revert "Add logging for query mode (#776)"

This reverts commit 7c94211.

Author: schmidt-sebastian

firebase-firestore/src/main/java/com/google/firebase/firestore/local/IndexFreeQueryEngine.java

@@ -24,7 +24,6 @@
 import com.google.firebase.firestore.model.DocumentKey;
 import com.google.firebase.firestore.model.MaybeDocument;
 import com.google.firebase.firestore.model.SnapshotVersion;
-import com.google.firebase.firestore.util.Logger;
 import java.util.Collections;
 import java.util.Map;
 
@@ -52,8 +51,6 @@
  * </ol>
  */
 public class IndexFreeQueryEngine implements QueryEngine {
-  private static final String LOG_TAG = "IndexFreeQueryEngine";
-
   private LocalDocumentsView localDocumentsView;
 
   @Override
@@ -86,14 +83,6 @@ && needsRefill(previousResults, remoteKeys, queryData.getLastLimboFreeSnapshotVe
       return executeFullCollectionScan(query);
     }
 
-    if (Logger.isDebugEnabled()) {
-      Logger.debug(
-          LOG_TAG,
-          "Re-using previous result from %s to execute query: %s",
-          queryData.getLastLimboFreeSnapshotVersion().toString(),
-          query.toString());
-    }
-
     // Retrieve all results for documents that were updated since the last limbo-document free
     // remote snapshot.
     ImmutableSortedMap<DocumentKey, Document> updatedResults =
@@ -172,9 +161,6 @@ public void handleDocumentChange(MaybeDocument oldDocument, MaybeDocument newDoc
   }
 
   private ImmutableSortedMap<DocumentKey, Document> executeFullCollectionScan(Query query) {
-    if (Logger.isDebugEnabled()) {
-      Logger.debug(LOG_TAG, "Using full collection scan to execute query: %s", query.toString());
-    }
     return localDocumentsView.getDocumentsMatchingQuery(query, SnapshotVersion.NONE);
   }
 }