[FIR] Cleanup ACTUAL_MISSING reporting

The cleanup became possible after KT-62590
Review: https://jetbrains.team/p/kt/reviews/12750/timeline

`matchingCompatibilityToMembersMap.allMismatches()` is equivalent to
`ExpectActualMatchingCompatibility.MatchedSuccessfully !in
matchingCompatibilityToMembersMap`

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/declaration/FirExpectActualDeclarationChecker.kt

@@ -145,14 +145,10 @@ object FirExpectActualDeclarationChecker : FirBasicDeclarationChecker() {
 
         val source = declaration.source
         if (!declaration.isActual) {
-            if (matchingCompatibilityToMembersMap.allMismatches()) return
-
-            if (ExpectActualMatchingCompatibility.MatchedSuccessfully in matchingCompatibilityToMembersMap) {
-                if (checkActual) {
-                    reporter.reportOn(source, FirErrors.ACTUAL_MISSING, context)
-                }
-                return
+            if (checkActual && ExpectActualMatchingCompatibility.MatchedSuccessfully in matchingCompatibilityToMembersMap) {
+                reporter.reportOn(source, FirErrors.ACTUAL_MISSING, context)
             }
+            return
         }
 
         when {
@@ -297,10 +293,6 @@ object FirExpectActualDeclarationChecker : FirBasicDeclarationChecker() {
         )
     }
 
-    fun Map<out ExpectActualCompatibility<*>, *>.allMismatches(): Boolean {
-        return keys.all { it is ExpectActualMatchingCompatibility.Mismatch }
-    }
-
     // we don't require `actual` modifier on
     //  - annotation constructors, because annotation classes can only have one constructor
     //  - value class primary constructors, because value class must have primary constructor