fix(ci): add xdist_group(proxy_heavy) to prevent OOM in parallel proxy tests

- Add pytestmark = pytest.mark.xdist_group('proxy_heavy') to test_proxy_utils.py
- Change test_db_schema_migration.py from schema_migration to proxy_heavy group
- Add @pytest.mark.xdist_group('proxy_heavy') to test_proxy_server.py::test_health

Groups heavy proxy tests to run on same worker, avoiding worker OOM crashes.

Co-authored-by: Ishaan Jaff <ishaan-jaff@users.noreply.github.com>

tests/proxy_unit_tests/test_db_schema_migration.py

@@ -17,7 +17,7 @@ def schema_setup(postgresql_my):
     return postgresql_my
 
 
-@pytest.mark.xdist_group("schema_migration")
+@pytest.mark.xdist_group("proxy_heavy")
 def test_aaaasschema_migration_check(schema_setup, monkeypatch):
     """Test to check if schema requires migration"""
     # Set test database URL

tests/proxy_unit_tests/test_proxy_server.py

@@ -835,6 +835,7 @@ def test_add_new_model(client_no_auth):
         pytest.fail(f"LiteLLM Proxy test failed. Exception {str(e)}")
 
 
+@pytest.mark.xdist_group("proxy_heavy")
 def test_health(client_no_auth):
     global headers
     import logging

tests/proxy_unit_tests/test_proxy_utils.py

@@ -24,6 +24,8 @@ from litellm.proxy.litellm_pre_call_utils import (
     add_litellm_data_to_request,
 )
 
+pytestmark = pytest.mark.xdist_group("proxy_heavy")
+
 
 @pytest.fixture
 def mock_request(monkeypatch):