Fix issue with LHCbApp().OutputLevel
Fixes an issue exposed by Brunel!757 (merged), in which EventLoopMgr is wrongly configured when LHCbApp().OutputLevel is set.
Cherry-picked from !1906 (merged) on run2-patches
Fixes an issue exposed by Brunel!757 (merged), in which EventLoopMgr is wrongly configured when LHCbApp().OutputLevel is set.
Cherry-picked from !1906 (merged) on run2-patches