[Fleet] Normalise search behaviour across fleet tabs

[hop-dev]

Kibana version: 7.15

Browser version: All

Description of the problem including expected versus actual behavior:

There is a difference in the search and search error behaviour for the different fleet tabs:

• agents: search only performed when ⏎ is pressed, KQL syntax errors cause error toast
• agent policies: search is performed on every key stroke, errors are never displayed
• enrolment tokens: search is performed on every key stroke, errors are never displayed
• data streams: search only performed when ⏎ is pressed, KQL syntax errors cause error toast

we should normalise this behaviour so that all match, I personally believe that the approach where we only search on ⏎ is more intuitive as a user.

Steps to reproduce:

1. go to fleet
2. in the agents tab, type some text, press ⏎
3. notice a search is performed
4. go to the agent policies tab with the network tab open, notice on every keystroke a search is submitted

[elasticmachine]

Pinging @elastic/fleet (Team:Fleet)

[jlind23]

Closing as not relevant anymore. Feel free to reopen if needed