RecoUtils: Tweak MessageSvc.Format to ensure a blank space before WARNING

I found that with !38479 (merged) we sometimes get messages like:

ToolSvc.CombinedMuonT...MuonTrackSummaryHelperToolWARNING Inconsistent hole count: expected hits eta 2 phi 2 hits eta 1 phi 0 missed eta 1 phi 2 holes eta 1 phi 1 recalculated phi holes 1

eg no space between the component name and the word WARNING. This MR fixes this shortcoming.