ServieMonitor should use with higher precedence the readOnlyApiKey

[vitali-ipquants]

Hello Qdrant team,

If in the values.yaml are defined both apiKey and readOnlyApiKey it will be better if the ServiceMonitor refers to the read-only key. The Prometheus will be able to collect metrics with the read-only key, so there's no need to pass it the more powerful key.

Thank you

[arthurk]

Good catch! I've create a PR for it here https://github.com/qdrant/qdrant-helm/pull/221