CLN: remove unreachable branch (pandas-dev#32405)

Author: jbrockmendel

pandas/core/indexes/base.py

@@ -32,7 +32,6 @@
     is_categorical,
     is_categorical_dtype,
     is_datetime64_any_dtype,
-    is_datetime64tz_dtype,
     is_dtype_equal,
     is_extension_array_dtype,
     is_float,
@@ -2525,14 +2524,8 @@ def _union(self, other, sort):
             return other._get_reconciled_name_object(self)
 
         # TODO(EA): setops-refactor, clean all this up
-        if is_datetime64tz_dtype(self):
-            lvals = self._ndarray_values
-        else:
-            lvals = self._values
-        if is_datetime64tz_dtype(other):
-            rvals = other._ndarray_values
-        else:
-            rvals = other._values
+        lvals = self._values
+        rvals = other._values
 
         if sort is None and self.is_monotonic and other.is_monotonic:
             try: