FIR JS: add K2 variants of all other JS tests

except tests that are not possible to add without some modifications in
the test infra. See todos on the commented-out test declarations

compiler/testData/codegen/box/defaultArguments/convention/incWithDefaultInGetter.kt

@@ -1,4 +1,4 @@
-// IGNORE_BACKEND_K2: JVM_IR
+// IGNORE_BACKEND_K2: JVM_IR, JS_IR
 // FIR status: don't support legacy feature (prefix increment calls getter twice). fail 2: anone1
 var inc: String = ""
 

compiler/testData/codegen/box/defaultArguments/kt36853_fibonacci.kt

@@ -1,6 +1,6 @@
 // WITH_STDLIB
 
-// IGNORE_BACKEND_K2: JVM_IR
+// IGNORE_BACKEND_K2: JVM_IR, JS_IR
 // FIR status:
 //  java.lang.StackOverflowError
 //	at Nat$Companion$invoke$1.next(kt36853_fibonacci.kt:40) ...

compiler/testData/codegen/box/defaultArguments/useNextParamInLambdaTailrec.kt

@@ -1,5 +1,5 @@
 // IGNORE_BACKEND: JVM
-// IGNORE_BACKEND_K2: JVM_IR
+// IGNORE_BACKEND_K2: JVM_IR, JS_IR
 // FIR status: don't support legacy feature. UNINITIALIZED_PARAMETER y. See KT-49800
 tailrec fun foo(x: () -> String? = { y }, y: String = "fail"): String? {
     if (y == "start")