Misc: Drop test for implementing abstract members in expect-class

The "not implemented" error is not reported for such classes, so
quick fix is not available anymore (see KT-16099)

idea/testData/multiModuleQuickFix/implementMembersInHeaderClass/header/header.kt

@@ -1,8 +0,0 @@
-// "Implement members" "true"
-// DISABLE-ERRORS
-
-interface I {
-    fun foo()
-}
-
-expect class <caret>Bar : I

idea/testData/multiModuleQuickFix/implementMembersInHeaderClass/header/header.kt.after

@@ -1,10 +0,0 @@
-// "Implement members" "true"
-// DISABLE-ERRORS
-
-interface I {
-    fun foo()
-}
-
-expect class <caret>Bar : I {
-    override fun foo()
-}