RootCanal: Implement a timeout for receiving the response to a LE Scan request

Addresses the following scenario:
- host 1 starts active scan
- host 2 starts scannable advertisements
- host 1 sends scan request
- host 2 stops advertising

Previously the host 1 would never again perform
a successful scan request until being reset by the host.

Bug: 309467982
Test: atest rootcanal_ll_test
Flag: EXEMPT, host tool
Change-Id: Ib01c92526bf89daada20e5cbe37fdea119e985a7