Refactor ActiveMQ scaler config

[wozniakjan]

Refactor activemq scaler config using declarative parser from https://github.com/kedacore/keda/pull/5676

Checklist

• [x] I have verified that my change is according to the deprecations & breaking changes policy
• [x] Commits are signed with Developer Certificate of Origin (DCO - learn more)

Relates to https://github.com/kedacore/keda/issues/5797

[wozniakjan]

/run-e2e activemq Update: You can check the progress here

[wozniakjan]

/run-e2e activemq Update: You can check the progress here

[wozniakjan]

/run-e2e activemq Update: You can check the progress here