[FIR] Ignore failing test, improve DiagnosticKind, fix UPPER_BOUND

compiler/testData/diagnostics/tests/subtyping/kt2744.fir.kt

@@ -1,3 +1,3 @@
-class X : <!OTHER_ERROR!>S<!>
+class X : <!UNRESOLVED_REFERENCE!>S<!>
 
 fun f(l: List<X>) {}

compiler/testData/diagnostics/tests/subtyping/kt304.fir.kt

@@ -1,6 +1,6 @@
 //KT-304: Resolve supertype reference to class anyway
 
-open class Foo() : <!OTHER_ERROR, OTHER_ERROR, OTHER_ERROR!>Bar<!>() {
+open class Foo() : Bar() {
 }
 
 open class Bar<T>() {

compiler/testData/diagnostics/tests/subtyping/unresolvedSupertype.fir.kt

@@ -1,7 +1,7 @@
-interface A1 : <!OTHER_ERROR!>B<!>
+interface A1 : <!UNRESOLVED_REFERENCE!>B<!>
 
-interface A2 : <!OTHER_ERROR!>B<!>()
+interface A2 : <!UNRESOLVED_REFERENCE!>B<!>()
 
-class A3 : <!OTHER_ERROR!>B<!>, <!OTHER_ERROR!>B<!>
+class A3 : <!UNRESOLVED_REFERENCE!>B<!>, <!UNRESOLVED_REFERENCE!>B<!>
 
-enum class A4 : <!OTHER_ERROR!>B<!>
+enum class A4 : <!UNRESOLVED_REFERENCE!>B<!>