Revert "[tests] Fix obsolete type in TestGenerateFamilyFile"

This reverts commit a1702eb1a31ac7ba8e40c7e5b75c7b29badcac21.

Reason for revert: No appropriate implementation

Bug: T334714
Change-Id: I1d856b49f1bf24fc8f51de5ced8673ddba1086e2
---
M tests/generate_family_file_tests.py
1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/tests/generate_family_file_tests.py b/tests/generate_family_file_tests.py
index ea9e0b8..f219ac6 100755
--- a/tests/generate_family_file_tests.py
+++ b/tests/generate_family_file_tests.py
@@ -1,7 +1,7 @@
 #!/usr/bin/env python3
 """Test generate_family_file script."""
 #
-# (C) Pywikibot team, 2018-2023
+# (C) Pywikibot team, 2018-2022
 #
 # Distributed under the terms of the MIT license.
 #
@@ -37,7 +37,7 @@
         """Pass writing."""
 
 
-class TestGenerateFamilyFile(DefaultSiteTestCase):
+class TestGenerateFamilyFiles(DefaultSiteTestCase):
 
     """Test generate_family_file functionality."""
 
@@ -80,9 +80,7 @@
             with self.subTest(test='Test element counts'):
                 if self.site.lang not in gen.prefixes:
                     gen.prefixes.append(self.site.lang)
-
-                # interwiki_removals is either a frozen_set or a list
-                obsolete = set(self.site.family.interwiki_removals)
+                obsolete = self.site.family.interwiki_removals
                 self.assertCountEqual(set(gen.prefixes) - obsolete,
                                       set(gen.wikis) - obsolete)
 

