[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/declarations/contextReceivers/plusMatrix.kt

@@ -1,8 +1,7 @@
 // FIR_IDENTICAL
 // !LANGUAGE: +ContextReceivers
 // !DIAGNOSTICS: -UNUSED_PARAMETER
-// IGNORE_BACKEND: JS_IR
-// IGNORE_BACKEND: JS_IR_ES6
+
 interface NumberOperations {
     fun Number.plus(other: Number): Number
 }