Provide a unique name while installing

[thisthat]

Tech details

Jmeter-service should provide a unique name while installing itself so that it can be easily installed in multiple remote-exec planes.
Users can still use nameOverride to provide their own name.

Acceptance Criteria

• When installing, jmeter-service creates a random alphanumeric string of 10chars that's appended to the integration name used to subscribe to the Keptn control plane
• The generated string is stored in a ConfigMap
• If the ConfigMap already exists, jmeter-service uses the secret value instead of the generated one
• if nameOverride is set via Helm value, it has precedence over the generated name

DoD

• Jmeter-service has a unique name on the Keptn control-plane when it is installed
• Updates of the integration do not change the integration name

Resources

Further information is available at keptn/keptn#8576