Add some new String methods in JDK 11 to built-ins mapping blacklist

These three methods are conflicting with existing extensions,
thus the behavior might be changed when switching to JDK 11

Probably, it's worth revisiting our strategy here,
e.g. by blacklisting all new methods in

 #KT-24974 Fixed

compiler/tests-common/tests/org/jetbrains/kotlin/test/TestJdkKind.java

@@ -20,6 +20,7 @@ public enum TestJdkKind {
     MOCK_JDK,
     // Differs from common mock JDK only by one additional 'nonExistingMethod' in Collection and constructor from Double in Throwable
     // It's needed to test the way we load additional built-ins members that neither in black nor white lists
+    // Also, now it contains new methods in java.lang.String introduced in JDK 11
     MODIFIED_MOCK_JDK,
     // JDK found at $JDK_16
     FULL_JDK_6,