Disable tests for indexers

Author: AlekseyTs

src/Compilers/CSharp/Portable/Lowering/LocalRewriter/LocalRewriter_IndexerAccess.cs

@@ -612,6 +612,7 @@ private BoundExpression GetUnderlyingIndexerOrSliceAccess(
                     // callers do the caching instead
                     // Tracked by https://github.com/dotnet/roslyn/issues/71056
                     AddPlaceholderReplacement(argumentPlaceholder, integerArgument);
+                    // https://github.com/dotnet/roslyn/issues/78829 - Do we need to do something special for recievers of extension indexers here?
                     ImmutableArray<BoundExpression> rewrittenArguments = VisitArgumentsAndCaptureReceiverIfNeeded(
                         ref receiver,
                         forceReceiverCapturing: false,