[FIR][tests] Unify IntArrayAsVararg.kt test between K1 and K2

Rename `main` function to `test` to avoid running JVM-specific mangling
and having different IR signature dumps for K1 and K2.

^KT-65588

compiler/testData/ir/irText/firProblems/IntArrayAsVararg.fir.sig.kt.txt

@@ -1,17 +0,0 @@
-// CHECK:
-//   Mangled name: #consumeVarargs(kotlin.IntArray...){}
-//   Public signature: /consumeVarargs|2702777436513705083[0]
-//   Public signature debug description: consumeVarargs(kotlin.IntArray...){}
-fun consumeVarargs(vararg arr: Int): Unit
-
-// CHECK JVM_IR:
-//   Mangled name: #main(){}
-//   Mangled name for the signature by IR:       main(){}
-//   Mangled name for the signature by Frontend: main(){}%IntArrayAsVararg.kt
-//   Public signature: /main|-4284757841571462650[0]
-//   Public signature debug description: main(){}
-// CHECK JS_IR NATIVE:
-//   Mangled name: #main(){}
-//   Public signature: /main|-4284757841571462650[0]
-//   Public signature debug description: main(){}
-fun main(): Unit

compiler/testData/ir/irText/firProblems/IntArrayAsVararg.ir.txt

@@ -1,5 +1,5 @@
 FILE fqName:<root> fileName:/IntArrayAsVararg.kt
-  FUN name:main visibility:public modality:FINAL <> () returnType:kotlin.Unit
+  FUN name:test visibility:public modality:FINAL <> () returnType:kotlin.Unit
     BLOCK_BODY
       CALL 'public final fun consumeVarargs (vararg arr: kotlin.Int): kotlin.Unit declared in <root>' type=kotlin.Unit origin=null
         arr: VARARG type=kotlin.IntArray varargElementType=kotlin.Int

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

@@ -2,10 +2,7 @@
 // WITH_STDLIB
 // ISSUE: KT-60312
 
-// SEPARATE_SIGNATURE_DUMP_FOR_K2
-// ^ The main function has a different mangled name when it's computed from its K1 descriptor in K/JVM.
-
-fun main() {
+fun test() {
     consumeVarargs(1, 2)
     consumeVarargs(arr = intArrayOf(41, 42))
 }

compiler/testData/ir/irText/firProblems/IntArrayAsVararg.kt.txt

@@ -1,4 +1,4 @@
-fun main() {
+fun test() {
   consumeVarargs(arr = [1, 2])
   consumeVarargs(arr = [*intArrayOf(elements = [41, 42])])
 }

compiler/testData/ir/irText/firProblems/IntArrayAsVararg.sig.kt.txt

@@ -4,16 +4,10 @@
 //   Public signature debug description: consumeVarargs(kotlin.IntArray...){}
 fun consumeVarargs(vararg arr: Int): Unit
 
-// CHECK JVM_IR:
-//   Mangled name: #main(){}
-//   Mangled name for the signature by IR:       main(){}
-//   Mangled name for the signature by Frontend: main(){}%IntArrayAsVararg.kt
-//   Public signature by IR: /main|-4284757841571462650[0]
-//   Public signature by IR debug description: main(){}
-//   Public signature by Frontend: /main|-2337641484263297417[0]
-//   Public signature by Frontend debug description: main(){}%IntArrayAsVararg.kt
-// CHECK JS_IR NATIVE:
-//   Mangled name: #main(){}
-//   Public signature: /main|-4284757841571462650[0]
-//   Public signature debug description: main(){}
-fun main(): Unit
+// CHECK:
+//   Mangled name: #test(){}
+//   Public signature: /test|6620506149988718649[0]
+//   Public signature debug description: test(){}
+fun test(): Unit
+
+