* Merge RubyGems-3.5.6 and Bundler-2.5.6

* Merge RubyGems-3.5.7 and Bundler-2.5.7

* Merge RubyGems-3.5.8 and Bundler-2.5.8

* Partly reverted about https://github.com/rubygems/rubygems/pull/7483

* Merge RubyGems-3.5.9 and Bundler-2.5.9

https://github.com/rubygems/rubygems/commit/99d91c9ed2

Signed-off-by: Takuya Noguchi <takninnovationresearch@gmail.com>

This changes "test/rubygems/test_case.rb" to "test/rubygems/helper.rb",
and "test/rubygems/test_utilities.rb" to "test/rubygems/utilities.rb".

The two files are a helper for tests, not test files. However, a file
starting with "test_" prefix is handled as a test file directly loaded
by test-unit because Rakefile specifies:

```
t.test_files = FileList['test/**/test_*.rb']
```

Directly loading test/rubygems/test_utilities.rb caused "uninitialized
constant Gem::TestCase". This issue was fixed by
59c682097197fee4052b47e4b4ab86562f3eaa9b, but the fix caused a
"circular require" warning because test_utilities.rb and test_case.rb
are now requiring each other.

Anyway, adding "test_" prefix to a test helper file is confusing, so
this changeset reverts the fix and solve the issue by renaming them.

https://github.com/rubygems/rubygems/commit/6460e018df