api: Use io.grpc.Uri for target parsing in ManagedChannelRegistry

Author: jdcormie

api/src/main/java/io/grpc/ManagedChannelRegistry.java

@@ -160,8 +160,11 @@ ManagedChannelBuilder<?> newChannelBuilder(NameResolverRegistry nameResolverRegi
       String target, ChannelCredentials creds) {
     NameResolverProvider nameResolverProvider = null;
     try {
-      URI uri = new URI(target);
-      nameResolverProvider = nameResolverRegistry.getProviderForScheme(uri.getScheme());
+      String scheme =
+          InternalFeatureFlags.getRfc3986UrisEnabled()
+              ? Uri.parse(target).getScheme()
+              : new URI(target).getScheme();
+      nameResolverProvider = nameResolverRegistry.getProviderForScheme(scheme);
     } catch (URISyntaxException ignore) {
       // bad URI found, just ignore and continue
     }