gh-40862: remove deprecated aliases in real_set
    
after File: src/sage/sets/real_set.py ; PR: #31927 ; Closed Date:
2021-06-29

### 📝 Checklist

- [x] The title is concise and informative.
- [x] The description explains in detail what this PR is about.
- [x] I have linked a relevant issue or discussion.
    
URL: #40862
Reported by: Frédéric Chapoton
Reviewer(s): David Coudert

Author: Release Manager

src/sage/sets/real_set.py

@@ -96,18 +96,17 @@ class RealSet.
 # (at your option) any later version.
 #                  https://www.gnu.org/licenses/
 # ****************************************************************************
+from heapq import merge
 
-from sage.structure.richcmp import richcmp, richcmp_method
-from sage.structure.parent import Parent
-from sage.structure.unique_representation import UniqueRepresentation
-from sage.categories.topological_spaces import TopologicalSpaces
 from sage.categories.sets_cat import EmptySetError
-from sage.sets.set import Set_base, Set_boolean_operators, Set_add_sub_operators
+from sage.categories.topological_spaces import TopologicalSpaces
+from sage.rings.infinity import infinity, minus_infinity
 from sage.rings.integer_ring import ZZ
 from sage.rings.real_lazy import LazyFieldElement, RLF
-from sage.rings.infinity import infinity, minus_infinity
-from sage.misc.superseded import deprecated_function_alias
-from heapq import merge
+from sage.sets.set import Set_base, Set_boolean_operators, Set_add_sub_operators
+from sage.structure.parent import Parent
+from sage.structure.richcmp import richcmp, richcmp_method
+from sage.structure.unique_representation import UniqueRepresentation
 
 
 @richcmp_method
@@ -2354,8 +2353,6 @@ def is_subset(self, *other):
         """
         return RealSet(*other).intersection(self) == self
 
-    is_included_in = deprecated_function_alias(31927, is_subset)
-
     def _an_element_(self):
         """
         Return a point of the set.
@@ -2601,8 +2598,6 @@ def is_disjoint(self, *other):
         other = RealSet(*other)
         return self.are_pairwise_disjoint(self, other)
 
-    is_disjoint_from = deprecated_function_alias(31927, is_disjoint)
-
     @staticmethod
     def are_pairwise_disjoint(*real_set_collection):
         """