[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.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
+
+