[inspections] PY-85120 Do not consider expressions like a: list[int] | None = None a type alias

Target expression should have either explicit `TypeAlias` annotation or valid type expression in assignment without type annotation (to be considered implicit type alias)

(cherry picked from commit 1059a8df2d221bd068eee706139be20c256df549)

GitOrigin-RevId: 8c952138fbc4124f02f717ce8a1784c1f0dc86b2

python/testSrc/com/jetbrains/python/inspections/PyTypeHintsInspectionTest.java

@@ -3189,6 +3189,16 @@ public class PyTypeHintsInspectionTest extends PyInspectionTestCase {
                    """);
   }
 
+  // PY-85120
+  public void testTargetExpressionWithAnnotationNotConsideredTypeAlias() {
+    doTestByText("""
+                   a: list[int] | None = None  # Not a type alias
+                   
+                   if a:
+                       _ = a[1]  # No error expected
+                   """);
+  }
+
   @NotNull
   @Override
   protected Class<? extends PyInspection> getInspectionClass() {