[IR] Don't print flags in declaration references in irText tests

This doesn't reduce the quality of tests, because the flags are still
printed for declarations themselves. We only omit them in references.

However, this makes the tests more compatible with non-JVM backends
(see KT-58605), because flags of referenced stdlib declarations may
differ among target platforms.

compiler/testData/ir/irText/classes/dataClasses/dataClasses.kt

@@ -1,6 +1,3 @@
-// IGNORE_BACKEND: JS_IR
-// IGNORE_BACKEND: JS_IR_ES6
-
 data class Test1(val x: Int, val y: String, val z: Any)
 
 data class Test2(val x: Any?)