Simplify (re-)start procedure

[hsakulin]

The procedure give in the OnCall HowTos is too cumbersome. The queries should be done automatically at startup.

[gladky]

Done with https://github.com/cmsdaq/DAQExpert/commit/90e53f8c023981c26fa436b55570735f003b3074

Following clean-startup check on DAQExpert start was added:

• if there is another DAQExpert is running interrupt current instance startup
• if another instance of DAQExpert crashed in the past and left DB in dirty state (some condition entries are not finished due to crash), perform cleanup automatically and continue startup.
• if no other instance of DAQExpert is running and DB is in clear state (graceful stop of previous process) continue startup

Note that in the second case the startup procedure will take a bit longer (additional 30 seconds) to make sure that in fact no other DAQExpert process is running.