ref: enable codecov data for tests/ (#82196)

I would like to see dead code in tests

<!-- Describe your PR here. -->

Author: asottile-sentry

codecov.yml

@@ -25,7 +25,6 @@ coverage:
     - static/app/routes.tsx
     - static/app/**/*.stories.tsx
     - static/app/**/__stories__/
-    - tests/
 
 component_management:
   individual_components:

tests/sentry/dynamic_sampling/test_generate_rules.py

@@ -724,7 +724,7 @@ def test_generate_rules_return_custom_rules(get_blended_sample_rate, default_old
 
     # no custom rule requests ==> no custom rules
     rules = generate_rules(default_old_project)
-    # only the BOOST_LOW_VOLUME_PROJECTS_RULE should be around (allways on)
+    # only the BOOST_LOW_VOLUME_PROJECTS_RULE should be around (always on)
     assert len(rules) == 1
     assert rules[0]["id"] == 1000