ci: fix tornado flakyness (#6610)

CI: Fix flaky tornado tests, ensure futures is patched before test runs.
This will ensure spans are correlated as expected.

## Checklist
- [x] Change(s) are motivated and described in the PR description.
- [x] Testing strategy is described if automated tests are not included
in the PR.
- [x] Risk is outlined (performance impact, potential for breakage,
maintainability, etc).
- [x] Change is maintainable (easy to change, telemetry, documentation).
- [x] [Library release note
guidelines](https://ddtrace.readthedocs.io/en/stable/releasenotes.html)
are followed. If no release note is required, add label
`changelog/no-changelog`.
- [x] Documentation is included (in-code, generated user docs, [public
corp docs](https://github.com/DataDog/documentation/)).
- [x] Backport labels are set (if
[applicable](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting))

## Reviewer Checklist

- [x] Title is accurate.
- [x] No unnecessary changes are introduced.
- [x] Description motivates each change.
- [x] Avoids breaking
[API](https://ddtrace.readthedocs.io/en/stable/versioning.html#interfaces)
changes unless absolutely necessary.
- [x] Testing strategy adequately addresses listed risk(s).
- [x] Change is maintainable (easy to change, telemetry, documentation).
- [x] Release note makes sense to a user of the library.
- [x] Reviewer has explicitly acknowledged and discussed the performance
implications of this PR as reported in the benchmarks PR comment.
- [x] Backport labels are set in a manner that is consistent with the
[release branch maintenance
policy](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting)

---------

Co-authored-by: Munir Abdinur <munir_abdinur@hotmail.com>

tests/contrib/tornado/utils.py

@@ -2,6 +2,8 @@
 
 from ddtrace.contrib.tornado import patch
 from ddtrace.contrib.tornado import unpatch
+from ddtrace.contrib.futures import patch as patch_futures
+from ddtrace.contrib.futures import unpatch as unpatch_futures
 from ddtrace.internal.compat import reload_module
 from tests.utils import TracerTestCase
 
@@ -19,6 +21,7 @@ class TornadoTestCase(TracerTestCase, AsyncHTTPTestCase):
     def get_app(self):
         # patch Tornado and reload module app
         patch()
+        patch_futures()
         reload_module(compat)
         reload_module(app)
 
@@ -37,5 +40,6 @@ def tearDown(self):
         super(TornadoTestCase, self).tearDown()
         # unpatch Tornado
         unpatch()
+        unpatch_futures()
         reload_module(compat)
         reload_module(app)