tests: pin deployed charms to a CKF 1.8 compatible version

This commit pins all charms that get deployed from Charmhub to a compatible version to the CKF 1.8 release.
This commit also refactors the test file so it takes all versions and other constants from a constants.py file

Part of canonical/bundle-kubeflow#863

tests/integration/test_charms.py

@@ -20,6 +20,14 @@
 UI_APP_NAME = UI_METADATA["name"]
 DB_APP_NAME = DB_METADATA["name"]
 
+MYSQL_K8S = "mysql-k8s"
+MYSQL_K8S_CHANNEL = "8.0/edge"
+MYSQL_K8S_TRUST = True
+
+KUBEFLOW_PROFILES = "kubeflow-profiles"
+KUBEFLOW_PROFILES_CHANNEL = "latest/edge"
+KUBEFLOW_PROFILES_TRUST = True
+
 logger = logging.getLogger(__name__)
 
 
@@ -47,9 +55,11 @@ async def test_deploy_katib_charms(ops_test: OpsTest):
 
     # Deploy katib-db
     await ops_test.model.deploy(
-        "charmed-osm-mariadb-k8s",
+        MYSQL_K8S,
+        channel=MYSQL_K8S_CHANNEL,
         application_name="katib-db",
         config={"database": "katib"},
+        trust=MYSQL_K8S_TRUST,
     )
 
     # Relate to katib-db
@@ -63,9 +73,9 @@ async def test_deploy_katib_charms(ops_test: OpsTest):
 
     # Deploy charms responsible for CRDs creation
     await ops_test.model.deploy(
-        entity_url="kubeflow-profiles",
-        channel="latest/edge",
-        trust=True,
+        entity_url=KUBEFLOW_PROFILES,
+        channel=KUBEFLOW_PROFILES_CHANNEL,
+        trust=KUBEFLOW_PROFILES_TRUST,
     )
 
     # Wait for everything to deploy

tests/integration/test_katib_experiments.py

@@ -27,7 +27,9 @@
     kind="Profile",
     plural="profiles",
 )
-TRAINING_CHARM = "training-operator"
+TRAINING_OPERATOR = "training-operator"
+TRAINING_OPERATOR_CHANNEL = "latest/edge"
+TRAINING_OPERATOR_TRUST = True
 
 
 @pytest.fixture(scope="module")
@@ -42,12 +44,12 @@ def lightkube_client() -> lightkube.Client:
 async def training_operator(ops_test: OpsTest):
     """Deploy training-operator charm, and wait until it's active."""
     await ops_test.model.deploy(
-        entity_url=TRAINING_CHARM,
-        channel="latest/edge",
-        trust=True,
+        entity_url=TRAINING_OPERATOR,
+        channel=TRAINING_OPERATOR_CHANNEL,
+        trust=TRAINING_OPERATOR_TRUST,
     )
     await ops_test.model.wait_for_idle(
-        apps=[TRAINING_CHARM], status="active", raise_on_blocked=False, timeout=60 * 5
+        apps=[TRAINING_OPERATOR], status="active", raise_on_blocked=False, timeout=60 * 5
     )