[lldb-dap] Unify the timeouts for the DAP tests (#163292)
Various DAP tests are specifying their own timeouts, with values ranging
from "1" to "20". Most of them seem arbitrary, but some come with a
comment.
The performance characters of running these tests in CI are
unpredictable (they generally run much slower than developers expect)
and really not something we can make assumptions about. I suspect these
timeouts are a contributing factor to the flakiness of the DAP tests.
This PR unifies the timeouts around a central value in the DAP server.
Fixes #162523
