ref: fix test pollution caused by leaked cache (#52345)
fixes this error in several other tests:
```
Traceback (most recent call last):
File "/home/runner/work/sentry/sentry/.venv/lib/python3.8/site-packages/django/core/handlers/exception.py", line 34, in inner
response = get_response(request)
File "/home/runner/work/sentry/sentry/.venv/lib/python3.8/site-packages/django/core/handlers/base.py", line 115, in _get_response
response = self.process_exception_by_middleware(e, request)
File "/home/runner/work/sentry/sentry/.venv/lib/python3.8/site-packages/django/core/handlers/base.py", line 113, in _get_response
response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/home/runner/work/sentry/sentry/.venv/lib/python3.8/site-packages/django/views/generic/base.py", line 71, in view
return self.dispatch(request, *args, **kwargs)
File "/home/runner/work/sentry/sentry/.venv/lib/python3.8/site-packages/django/views/decorators/csrf.py", line 54, in wrapped_view
return view_func(*args, **kwargs)
File "/home/runner/work/sentry/sentry/src/sentry/web/frontend/base.py", line 338, in dispatch
return self.handle(request, *args, **kwargs)
File "/home/runner/work/sentry/sentry/src/sentry/web/frontend/base.py", line 356, in handle
return super().dispatch(request, *args, **kwargs)
File "/home/runner/work/sentry/sentry/.venv/lib/python3.8/site-packages/django/views/generic/base.py", line 97, in dispatch
return handler(request, *args, **kwargs)
File "/home/runner/work/sentry/sentry/src/sentry/web/frontend/auth_logout.py", line 21, in get
return self.respond("sentry/logout.html")
File "/home/runner/work/sentry/sentry/src/sentry/web/frontend/base.py", line 405, in respond
return render_to_response(template, default_context, self.request, status=status)
File "/home/runner/work/sentry/sentry/src/sentry/web/helpers.py", line 40, in render_to_response
response = HttpResponse(render_to_string(template, context, request))
File "/home/runner/work/sentry/sentry/src/sentry/web/helpers.py", line 27, in render_to_string
rendered = loader.render_to_string(template, context=context, request=request)
File "/home/runner/work/sentry/sentry/.venv/lib/python3.8/site-packages/django/template/loader.py", line 62, in render_to_string
return template.render(context, request)
File "/home/runner/work/sentry/sentry/.venv/lib/python3.8/site-packages/django/template/backends/django.py", line 61, in render
return self.template.render(context)
File "/home/runner/work/sentry/sentry/.venv/lib/python3.8/site-packages/django/template/base.py", line 171, in render
return self._render(context)
File "/home/runner/work/sentry/sentry/.venv/lib/python3.8/site-packages/django/test/utils.py", line 96, in instrumented_test_render
return self.nodelist.render(context)
File "/home/runner/work/sentry/sentry/.venv/lib/python3.8/site-packages/django/template/base.py", line 937, in render
bit = node.render_annotated(context)
File "/home/runner/work/sentry/sentry/.venv/lib/python3.8/site-packages/django/template/base.py", line 904, in render_annotated
return self.render(context)
File "/home/runner/work/sentry/sentry/.venv/lib/python3.8/site-packages/django/template/loader_tags.py", line 150, in render
return compiled_parent._render(context)
File "/home/runner/work/sentry/sentry/.venv/lib/python3.8/site-packages/django/test/utils.py", line 96, in instrumented_test_render
return self.nodelist.render(context)
File "/home/runner/work/sentry/sentry/.venv/lib/python3.8/site-packages/django/template/base.py", line 937, in render
bit = node.render_annotated(context)
File "/home/runner/work/sentry/sentry/.venv/lib/python3.8/site-packages/django/template/base.py", line 904, in render_annotated
return self.render(context)
File "/home/runner/work/sentry/sentry/.venv/lib/python3.8/site-packages/django/template/loader_tags.py", line 150, in render
return compiled_parent._render(context)
File "/home/runner/work/sentry/sentry/.venv/lib/python3.8/site-packages/django/test/utils.py", line 96, in instrumented_test_render
return self.nodelist.render(context)
File "/home/runner/work/sentry/sentry/.venv/lib/python3.8/site-packages/django/template/base.py", line 937, in render
bit = node.render_annotated(context)
File "/home/runner/work/sentry/sentry/.venv/lib/python3.8/site-packages/django/template/base.py", line 904, in render_annotated
return self.render(context)
File "/home/runner/work/sentry/sentry/.venv/lib/python3.8/site-packages/django/template/loader_tags.py", line 150, in render
return compiled_parent._render(context)
File "/home/runner/work/sentry/sentry/.venv/lib/python3.8/site-packages/django/test/utils.py", line 96, in instrumented_test_render
return self.nodelist.render(context)
File "/home/runner/work/sentry/sentry/.venv/lib/python3.8/site-packages/django/template/base.py", line 937, in render
bit = node.render_annotated(context)
File "/home/runner/work/sentry/sentry/.venv/lib/python3.8/site-packages/django/template/base.py", line 904, in render_annotated
return self.render(context)
File "/home/runner/work/sentry/sentry/.venv/lib/python3.8/site-packages/django/template/library.py", line 192, in render
output = self.func(*resolved_args, **resolved_kwargs)
File "/home/runner/work/sentry/sentry/src/sentry/utils/assets.py", line 39, in get_frontend_app_asset_url
key = versions[key]
KeyError: 'sentry.css'
```
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anthony sottile