remove asset download count feature entirely

The repository health check asset download count feature often takes an excessive amount of space in customer databases.  This has been observed to lead to performance problems.

In the attached listing it can be seen that asset download tables are consuming 54% of the 4Gb component database.

Acceptance

• remove the asset download count feature supporting RHC completely from the product ( database tables, indexes, data, ui, integrations, etc. )
• coordinate with other teams as necessary to schedule their effort to update the templates including the download count graph

 NEXUS-18617 - disables using the feature by default in 3.15.0, but the data, code and infrastructure still remains