Switch default JVM target to 1.8

#KT-29405 Fixed

compiler/testData/diagnostics/tests/j+k/inheritanceStaticMethodFromInterface.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 // FILE: I.java
 
 public interface I {
@@ -18,7 +19,7 @@ class K : C()
 
 fun main() {
     I.a
-    I.<!INTERFACE_STATIC_METHOD_CALL_FROM_JAVA6_TARGET_ERROR!>foo<!>()
+    I.foo()
 
     C.a
     C.b