Revert "[FIR] Fix missing RETURN_TYPE_MISMATCH for labeled return statements"

This reverts commit 8e72f60996

Since some intellij tests are failing

compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnNoCoercionToUnit.fir.kt

@@ -1,6 +1,6 @@
 fun test(a: Int) {
     run f@{
-      if (a > 0) <!RETURN_TYPE_MISMATCH!>return@f<!>
+      if (a > 0) return@f
       else return@f 1
     }
 }

compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnSecondUnit.fir.kt

@@ -0,0 +1,6 @@
+val flag = true
+
+val a = b@ {
+    if (flag) return@b 4
+    return@b
+}

compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnSecondUnit.kt

@@ -1,7 +1,6 @@
-// FIR_IDENTICAL
 val flag = true
 
 val a = b@ {
     if (flag) return@b <!RETURN_TYPE_MISMATCH!>4<!>
     return@b
-}
+}

compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnUnitAndDontCareType.fir.kt

@@ -14,7 +14,7 @@ val b = run {
 
 // Unit
 val c = run {
-    if (flag) <!RETURN_TYPE_MISMATCH!>return@run<!>
+    if (flag) return@run
 
     return@run 4
-}
+}

compiler/testData/diagnostics/tests/functionLiterals/return/LocalReturnsWithExplicitReturnType.fir.kt

@@ -1,6 +1,6 @@
 fun test(a: Int) {
     run<Int>f@{
-      if (a > 0) return@f <!ARGUMENT_TYPE_MISMATCH, RETURN_TYPE_MISMATCH!>""<!>
+      if (a > 0) return@f <!ARGUMENT_TYPE_MISMATCH!>""<!>
       return@f 1
     }