Revert "JVM_IR indy-SAM: use '-Xsam-conversions=indy' if JVM 1.8+, LV 1.5+"

This reverts commit 679756ad

compiler/testData/codegen/java9/box/kt36984.kt

@@ -1,6 +1,4 @@
 // TARGET_BACKEND: JVM
-// IGNORE_BACKEND: JVM_IR
-//  ^ JVM_IR back-end generates SAM conversion with invokedynamic
 // WITH_RUNTIME
 
 fun box(): String {
@@ -15,4 +13,4 @@ fun box(): String {
         throw Exception("!samJavaClass.isAnonymousClass(): '${samJavaClass.name}'")
 
     return "OK"
-}
+}