Addon provider cannot handle values sources with long names

[sd109]

Because the addon provider uses labels on the HelmRelease objects to know which secrets & config maps to watch for changes, and because label names are limited to 63 characters, watching secrets or config maps with long names causes reconciliation to fail with errors such as:

  Error   Logging  7m2s  kopf  Handler 'handle_addon_updated' failed permanently: HelmRelease.addons.stackhpc.com "project-test-cluster-bqb6ktvxag34-mellanox-network-operator" is invalid: metadata.labels: Invalid value: "secret.addons.stackhpc.com/project-test-cluster-bqb6ktvxag34-mellanox-network-operator-config": name part must be no more than 63 characters

The temporary solution is to create clusters with shorter names... but we should try to handle this better in the operator.