FIR: simplify problematic test

compiler/fir/resolve/testData/resolve/problems/covariantArrayAsReceiver.kt

@@ -17,7 +17,6 @@ fun <T> Array<out T>.filterNot(f: (T) -> Boolean): List<T> {
 fun <T> Array<T>.toList(): List<T>? = null
 
 fun foo(element: PsiElement, usages: Array<UsageInfo>) {
-    element is KtLightMethod
     val adjusted = if (element is KtParameter) usages.filterNot {
         it.usage is KtLightMethod
     } else usages.toList()

compiler/fir/resolve/testData/resolve/problems/covariantArrayAsReceiver.txt

@@ -17,7 +17,6 @@ FILE: covariantArrayAsReceiver.kt
         ^toList Null(null)
     }
     public final fun foo(element: R|PsiElement|, usages: R|kotlin/Array<UsageInfo>|): R|kotlin/Unit| {
-        (R|<local>/element| is R|KtLightMethod|)
         lval adjusted: R|kotlin/collections/List<UsageInfo>?| = when () {
             (R|<local>/element| is R|KtParameter|) ->  {
                 R|<local>/usages|.R|/filterNot|<R|UsageInfo|>(<L> = filterNot@fun <implicit>.<anonymous>(): <implicit> {