Fix compiler and IDE tests on Experimental/RequiresOptIn

See cdbabf224f, e009c7064e

idea/testData/quickfix/experimental/basicUseExperimental.kt

@@ -1,4 +1,4 @@
-// "Add '@UseExperimental(MyExperimentalAPI::class)' annotation to 'bar'" "true"
+// "Add '@OptIn(MyExperimentalAPI::class)' annotation to 'bar'" "true"
 // COMPILER_ARGUMENTS: -Xuse-experimental=kotlin.Experimental
 // WITH_RUNTIME
 
@@ -17,4 +17,4 @@ class Bar {
     fun bar() {
         Some().foo<caret>()
     }
-}
+}