Update CRD to remove role, user (name), and lengthen generated password in liew of setting it

During the previous messaging operators virtual team meeting there was discussion over inclusion of items in the CRD which at the moment do not add any value from the end users perspective. These included those included directly in the issue title, as setting any of these only gives the user the illusion of control and really don't make that much of a difference at the moment.

As well we discussed removing 'clustered' once again, and the conclusion was:

• removing it now and adding it later is simpler from a CRD versioning perspective than having it now and removing it later
• the most general expectation will be that with brokers size > 1 clustering is enabled

Note that the clustering change effectively means that operator-based deployments larger than one broker are clustered by default.