Use mock JDK in compiler tests where full JDK is not needed

- move some of boxWithStdlib tests under fullJdk/ directory, where they will be
  compiled against the full JDK
- introduce FULL_JDK in-text directive for the reflection test as only 4 tests
  out of 654 needed the full JDK

compiler/testData/loadJava/compiledKotlin/fromLoadJava/modality/ModalityOfFakeOverrides.kt

@@ -1,3 +1,4 @@
+// FULL_JDK
 package test
 
 import java.util.AbstractList