Make Auto Format Search Togglable and Add UI Search Warning

When a user goes to a 'Search --> <Format>' page in the UI e.g. /#browse/search/maven, an automatic search is performed to return 300 results for artifacts of the given format.

In cases where there are a large number of repos and/or large number of artifacts of the given format, this page can take a long time to load (>60s) and can result in a UI timeout as well as an increase in CPU usage.

The UI timeout can be resolved by increasing the request timeout, but the potential exists for the instance to experience CPU related performance problems if multiple users perform the same query at the same time.

Based on this, the option should exist for large(er) instances to disable/prevent the automatic search that is performed by visiting a format search page.

In addition to this, an explicit user search also has the potential to be expensive and can result in a timeout and/or high CPU usage, therefore the UI Search pages should carry a warning/advisory informing users of this potential and advise that they attempt to perform  specific searches using the available filters.

Expected

Don't perform automatic behaviors that could have expensive performance implications.

if the solution is to not perform a search automatically when choosing a format, then make it clear in the UI that the user needs to explicitly enter some criteria and explicitly click something to perform a search instead. ( ie. don't just leave a blank screen where the user may believe some background search is happening but has not returned results yet )