QA Event feature still sends REST requests for each Item page visit when the feature is disabled

[ybnd]

Describe the bug

With qaevents.enabled=false in the REST configuration, each Item page visit continues to trigger a REST request for /server/api/integration/qualityassurancesources/search/byTarget.

This is especially problematic on older DSpace servers (before DSpace/DSpace#11525 and its backports), because each of those requests results in multiple HttpSolrClient instances getting created and never closed.

To Reproduce

Steps to reproduce the behavior:

1. Configure qaevents.enabled=false
2. Go to any Item page while monitoring the dspace.log

Expected behavior

When the feature is disabled, no requests related to the feature should be made.

Proposed solution

This can be implemented simply by:

• Exposing qaevents.enabled=false
• Only sending the /server/api/integration/qualityassurancesources/search/byTarget request if

There are probably similar cases elsewhere.

Related work

#5932