test(pricing): read the catalog through the test session only

The provider helper called reinitialize_upstreams(), which re-reads the
provider table through the global engine rather than the session the test
was handed. On a developer machine that engine finds keys.db and the call
is invisible; on a clean checkout there is no such database and every test
in the file fails with "no such table: upstream_providers".

Nothing here needs it: these tests call list_models() with the session
directly and never route a request, so the proxy's cached upstreams are
not part of what is under test. Dropping the call also stops the file
mutating that global for whatever runs next.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011cKHVF5LA7TR5QuYi6ErLM

tests/integration/test_served_catalog_rate_backstop.py

@@ -19,7 +19,6 @@ from sqlmodel.ext.asyncio.session import AsyncSession
 
 from routstr.core.db import ModelRow, UpstreamProviderRow
 from routstr.payment.models import list_models
-from routstr.proxy import reinitialize_upstreams
 
 _ARCHITECTURE = json.dumps(
     {
@@ -42,7 +41,6 @@ async def _make_provider(session: AsyncSession) -> int:
     session.add(provider)
     await session.commit()
     await session.refresh(provider)
-    await reinitialize_upstreams()
     assert provider.id is not None
     return provider.id