Test scenario when changing the Connected Monitoring instance on SCC-WP

[ocofaigh]

We have been told that changing the connected Monitoring instance is not supported and cause issues if attempted. We should test the following:

1. Deploy SCC-WP and pass a value for cloud_monitoring_instance_crn to connect a Cloud Monitoring instance (from same region as SCC-WP)
2. After succesfull deploy, change the value of cloud_monitoring_instance_crn and observe behaviour. Does the update fail the terraform? Does it pass terraform but integration itself breaks?

Based on our observations we may wish to prevent module / DA consumers from being able to do this (e.g. with lifecycle ignore, or something else)