[FIR] 2/2 Cleanup: drop no longer necessary FirActualCallableDeclarationChecker

It became possible to drop it after KT-62590. Now, on a frontend, the
return type check is part of a common AbstractExpectActualChecker logic

Change in nestedAnnotationClassViaActualTypealias.fir.kt aligns the
behaviour with K1. KT-61964

Review: https://jetbrains.team/p/kt/reviews/12750/timeline

compiler/resolution.common/src/org/jetbrains/kotlin/resolve/calls/mpp/AbstractExpectActualChecker.kt

@@ -362,22 +362,20 @@ object AbstractExpectActualChecker {
         val expectedValueParameters = expectDeclaration.valueParameters
         val actualValueParameters = actualDeclaration.valueParameters
 
-        if (shouldCheckReturnTypesOfCallables) {
-            val substitutor = createExpectActualTypeParameterSubstitutor(
-                (expectedTypeParameters zipIfSizesAreEqual actualTypeParameters)
-                    ?: error("expect/actual type parameters sizes are checked earlier"),
-                parentSubstitutor
-            )
+        val substitutor = createExpectActualTypeParameterSubstitutor(
+            (expectedTypeParameters zipIfSizesAreEqual actualTypeParameters)
+                ?: error("expect/actual type parameters sizes are checked earlier"),
+            parentSubstitutor
+        )
 
-            if (!areCompatibleExpectActualTypes(
-                    substitutor.safeSubstitute(expectDeclaration.returnType),
-                    actualDeclaration.returnType,
-                    parameterOfAnnotationComparisonMode = insideAnnotationClass,
-                    dynamicTypesEqualToAnything = false
-                )
-            ) {
-                return ExpectActualCheckingCompatibility.ReturnType
-            }
+        if (!areCompatibleExpectActualTypes(
+                substitutor.safeSubstitute(expectDeclaration.returnType),
+                actualDeclaration.returnType,
+                parameterOfAnnotationComparisonMode = insideAnnotationClass,
+                dynamicTypesEqualToAnything = false
+            )
+        ) {
+            return ExpectActualCheckingCompatibility.ReturnType
         }
 
         if (actualDeclaration.hasStableParameterNames && !equalsBy(expectedValueParameters, actualValueParameters) { it.name }) {

compiler/resolution.common/src/org/jetbrains/kotlin/resolve/calls/mpp/ExpectActualMatchingContext.kt

@@ -20,8 +20,6 @@ import org.jetbrains.kotlin.types.model.TypeSubstitutorMarker
 import org.jetbrains.kotlin.types.model.TypeSystemContext
 
 interface ExpectActualMatchingContext<T : DeclarationSymbolMarker> : TypeSystemContext {
-    val shouldCheckReturnTypesOfCallables: Boolean
-
     /*
      * This flag indicates how are type parameters of inner classes stored in the specific implementation of RegularClassSymbolMarker
      *