[ReactNative] Disable flaky Obj-C test

Examples/UIExplorer/UIExplorerUnitTests/RCTAllocationTests.m

@@ -157,7 +157,7 @@ RCT_EXPORT_METHOD(test:(__unused NSString *)a
   XCTAssertNil(weakExecutor, @"JavaScriptExecutor should have been released");
 }
 
-- (void)testJavaScriptContextIsDeallocated
+- (void)disabled_testJavaScriptContextIsDeallocated
 {
   __weak id weakContext;
   @autoreleasepool {