SECRET_KEY is not generated when deployment is created

[dkliban]

THe operator should allow users to provide a pulp-secret-key secret. If it is not provided a random SECRET_KEY should be generated for settings.py secret.

[git-hyagi]

https://docs.djangoproject.com/en/4.2/ref/settings/#secret-key

[git-hyagi]

Adding more context/information since not much was provided in the issue description:
From Django doc: "A secret key for a particular Django installation. This is used to provide cryptographic signing, and should be set to a unique, unpredictable value."

• We should provide a new field (string) in Pulp CR called PulpSecretKey (json:"pulp_secret_key").
• The field should be immutable.
• If PulpSecretKey field is not provided, the operator should create a new secret with a random string of length 50 from "abcdefghijklmnopqrstuvwxyz0123456789!@#$%^&*(-_=+)" chars.
• The operator should have a watcher to identify Secret content updates (pending definition of procedure in case of secret change).
• Update backup/restore controllers to handle this new Secret.

Pending definitions:

• should we keep it in the settings.py file or can we set a SECRET_KEY env var?
• which containers will need it? (api and content!?)
• what is the procedure to rotate the secret?

[dkliban]

Lets keep SECRET_KEY in /etc/pulp/settings.py

If it changes, all teh API nodes need to be restarted.