[IR] Don't print multifile/synthetic facade class names in irText tests

This only applies to JVM and fq-names in declaration references
in IR dumps.

This enables us to run more irText tests on platforms other than JVM
(see KT-58605).

compiler/testData/ir/irText/firProblems/DeepCopyIrTree.kt

@@ -1,7 +1,5 @@
 // WITH_STDLIB
 // FULL_JDK
-// IGNORE_BACKEND: JS_IR
-// IGNORE_BACKEND: JS_IR_ES6
 
 interface IrType