Interactive web terminal: add timeout before killing terminal on page refresh

Problem to solve

When a terminal is open, having a GC timeout of 30 minutes is good, but if you are on the terminal page, and you press F5 to reload (for whatever reason) the terminal get killed immediately.

Proposal

It would be good to wait for some time (at least 30 sec to a minute) before killing it.

Links / references

ZD: https://gitlab.zendesk.com/agent/tickets/104430 (internal)