Trace Postgres and Redis queries with the contrib instrumentations

Builds the TracerProvider in tavolo.telemetry (kaya-otel's is private) and
injects it into kaya-otel, then instruments asyncpg and redis through
opentelemetry-instrumentation-asyncpg/redis. Redis command values are
redacted and asyncpg spans carry the parameterized SQL only.

server/tests/test_otel.py

@@ -78,6 +78,15 @@ class OTelMixinFromSettingsTests(unittest.TestCase):
         assert isinstance(mixin, _StubOTelMixin)
         self.assertIs(provider, mixin.kwargs["meter_provider"])
 
+    def test_tracer_provider_is_passed_through(self):
+        with _stub_kaya_otel():
+            provider = object()
+            mixin = otel_mixin_from_settings(
+                _settings({"OTEL_ENABLED": "1"}), tracer_provider=provider
+            )
+        assert isinstance(mixin, _StubOTelMixin)
+        self.assertIs(provider, mixin.kwargs["tracer_provider"])
+
     def test_excluded_paths_are_passed_through(self):
         with _stub_kaya_otel():
             mixin = otel_mixin_from_settings(_settings({