HLT: Move DB connection managment from Psc to HltEventLoopMgr
Move the management of DB connections before forking from the Psc to
HltEventLoopMgr (ATR-8907). This allows the sleep time to be configured
via the new dbConnIdleWaitSec
property.
Moved the actual code to the TrigRDBManager
helper class so we don't
have to change the friend relationship in IRDBAccessSvc
in case we
need to move this code somewhere else again.