add TracksV1 into CounterJSON handler

According to the discussion https://gitlab.cern.ch/lhcb-rta/data-challenges/-/issues/7, we provide a new plot in PrCheckerCounterJSONhandler named TracksV1Tracks.

It includes the following items:

'Downstream':     total track number from `DownstreamTrackChecker`
'FittedForward':  total track number from `ForwardHlt1TrackChecker`
'Forward':        total track number from `ForwardTrackChecker`
'Match':          total track number from `MatchTrackChecker`
'Seeding':        total track number from `SeedTrackChecker`
'Upstream':       total track number from `UpstreamTrackChecker`
'Velo':           total track number from `VeloTrackChecker`

Other items need further discussion.

ps. We also reduce the font size of the X-title for display.

FYI @msaur @sklaver