[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/testData/multiplatform/classScopes/functionIncorrectSignature/output.txt

@@ -6,7 +6,7 @@ Output:
 Exit code: COMPILATION_ERROR
 Output:
 compiler/testData/multiplatform/classScopes/functionIncorrectSignature/jvm.kt:2:16: error: 'actual fun function(b: ByteArray): Long' has no corresponding expected declaration
-The following declaration is incompatible:
+The following declaration is incompatible because return type is different:
     expect fun function(b: ByteArray): Int
 
     actual fun function(b: ByteArray): Long = b.size.toLong()

compiler/testData/multiplatform/classScopes/functionIncorrectSignatureFromSuperclass/output.txt

@@ -5,9 +5,12 @@ Output:
 -- JVM --
 Exit code: COMPILATION_ERROR
 Output:
-compiler/testData/multiplatform/classScopes/functionIncorrectSignatureFromSuperclass/common.kt:1:1: error: expect declaration `Foo` doesn't match actual `Foo` because some expected members have no actual ones
-expect class Foo {
-^
-compiler/testData/multiplatform/classScopes/functionIncorrectSignatureFromSuperclass/common.kt:2:5: error: expect declaration `function` doesn't match actual `function` because return type is different
-    fun function(b: ByteArray): Int
-    ^
+compiler/testData/multiplatform/classScopes/functionIncorrectSignatureFromSuperclass/jvm.kt:5:14: error: 'actual class Foo : Base' has no corresponding members for expected class members:
+
+    expect fun function(b: ByteArray): Int
+
+    The following declaration is incompatible because return type is different:
+        fun function(b: ByteArray): Long
+
+actual class Foo : Base()
+             ^