[FIR] Call distinctBy for containsMultipleNonSubsumed

Otherwise, when analyzing
`PsiTypeParameterListOwner` in the
related test, we (after flattening and
`nonSubsumed()`) get 2 `JvmMember.accept`
from the same very java enhancement
scope `JvmMember`.

^KT-65972

compiler/fir/providers/src/org/jetbrains/kotlin/fir/declarations/declarationUtils.kt

@@ -160,6 +160,12 @@ fun MemberWithBaseScope<FirCallableSymbol<*>>.getNonSubsumedOverriddenSymbols():
         .map { it.member }
 }
 
+fun List<MemberWithBaseScope<FirCallableSymbol<*>>>.getNonSubsumedNonPhantomOverriddenSymbols(): List<MemberWithBaseScope<FirCallableSymbol<*>>> {
+    return flatMap { it.flattenPhantomIntersectionsRecursively() }
+        .nonSubsumed()
+        .distinctBy { it.member.unwrapSubstitutionOverrides<FirCallableSymbol<*>>() }
+}
+
 fun FirCallableSymbol<*>.dispatchReceiverScope(session: FirSession, scopeSession: ScopeSession): FirTypeScope {
     val dispatchReceiverType = requireNotNull(dispatchReceiverType)
     return dispatchReceiverType.scope(

compiler/fir/providers/src/org/jetbrains/kotlin/fir/scopes/impl/FirTypeIntersectionScopeContext.kt

@@ -180,8 +180,8 @@ class FirTypeIntersectionScopeContext(
                     overriddenMembers = group,
                     containingScope = null,
                     containsMultipleNonSubsumed = when {
-                        forClassUseSiteScope -> group.flatMap { it.flattenPhantomIntersectionsRecursively() }.nonSubsumed().size > 1
-                        else -> mostSpecific.flatMap { it.flattenPhantomIntersectionsRecursively() }.nonSubsumed().size > 1
+                        forClassUseSiteScope -> group.getNonSubsumedNonPhantomOverriddenSymbols().size > 1
+                        else -> mostSpecific.getNonSubsumedNonPhantomOverriddenSymbols().size > 1
                     },
                 )
             } else {