[bitnami/mlflow] chore: 👷 Add VIB integration (#50293)

* [bitnami/mlflow] chore: 👷 Add VIB integration

This PR adds basic goss tests to the MLflow container. Runs:

- Common tests
- Version test
- User tests
- MLflow tracking server test

Signed-off-by: Javier Salmeron Garcia <jsalmeron@vmware.com>

* test: ✅ Improve signal handling and permissions

In the `mlflow-serve` test, the timeout command must be changed to use
SIGINT as `mlflow server` does not behave correctly when using SIGTERM.

In the directory tests, the permissions of the `/opt/bitnami/python`
folder are more restricted

Signed-off-by: Javier Salmeron Garcia <jsalmeron@vmware.com>

---------

Signed-off-by: Javier Salmeron Garcia <jsalmeron@vmware.com>

.vib/mlflow/goss/vars.yaml

@@ -0,0 +1,14 @@
+binaries:
+  - python
+  - mlflow
+root_dir: /opt/bitnami
+directories:
+  - mode: "0755"
+    paths:
+      - /opt/bitnami/python
+  - mode: "0775"
+    paths:
+      - /app
+version:
+  bin_name: python
+  flag: "-c 'import mlflow; print(mlflow.__version__)'"