Add checking the dead time plot

[jheikkil]

We should be able to open also the total dead time plot, for example
https://cmswbm.cern.ch/cmsdb/servlet/ChartDeadtimeCounters?runID=306460&scalerID0=1

The shifter needs to check that dead time is not >10% for multiple LS.

[zhenbinwu]

That can be done with the WBM script. Does the shifter need to report this on the elog? Can't find the deadtime in the example elog