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/codegen/boxWithStdlib/annotations/jvmFlags.kt

@@ -1,21 +0,0 @@
-import java.lang.reflect.Modifier
-
-class C {
-    volatile var vol = 1
-    transient val tra = 1
-
-    strictfp fun str() {}
-    synchronized fun sync() {}
-}
-
-fun box(): String {
-    val c = javaClass<C>()
-
-    if (c.getDeclaredField("vol").getModifiers() and Modifier.VOLATILE == 0) return "Fail: volatile"
-    if (c.getDeclaredField("tra").getModifiers() and Modifier.TRANSIENT == 0) return "Fail: transient"
-
-    if (c.getDeclaredMethod("str").getModifiers() and Modifier.STRICT == 0) return "Fail: strict"
-    if (c.getDeclaredMethod("sync").getModifiers() and Modifier.SYNCHRONIZED == 0) return "Fail: synchronized"
-
-    return "OK"
-}