[DPE-5711] Add warnings to destructive actions

[sinclert-canonical]

This PR adds warning level messages when a destructive action is performed. The definition of destructive seems to be associated with data loss, which I think it can only happen, from user action, whenever they force a primary failover without checking considering the health of such instance.

Additional info

• Paulo confirmed that this ticket was created to familiarised myself with the codebases.
• Alex referenced this PostgreSQL operator PR as the reason behind the need for warnings.

[sinclert-canonical]

Can you please explain the benefits of merging this? Warning for force action?

I think that the upgrade action will not execute the upgrade if the unit is considered unhealthy (whatever that means). This action could be forced by using the --force flag, which, may lead to data-loss.

Can we warn it globally in a moment of setting force=True?

We could put it in the charm's _on_resume_upgrade_action method (only one that calls the Upgrade.reconcile_upgrade method with an event), but we would be raising warnings even if the upgrade is not actually executed. Do we want that?

[sinclert-canonical]

Added info messages to Workload._diable_router method.