Autocomplete dropdown load optimization

What does this MR do and why?

The dropdown API endpoint has been split into two to optimize the loading of the dropdown front end.

All MR parts:

• part 1 - Autocomplete dropdown load optimization
  • part 2 - Add skeleton loader to header search dropdown

Screenshots or screen recordings

How to set up and validate locally

1. checkout this branch
2. throttle the network speed (it highlights the issue)
3. search any term in the header search bar

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #361520 (closed)