[Bug] Remove JMX credentials generation from entrypoint script

[andrewazores]

Current Behavior

JMX credentials can and should be generated separately and mounted into the container. The container can be configured to pick up the user access file and user password file from the mounted location using JAVA_OPTS_APPEND. Therefore, there is no reason for the entrypoint script to generate these files at startup time.

See cryostatio/cryostat-operator#815

Expected Behavior

No response

Steps To Reproduce

No response

Environment

No response

Anything else?

No response