Add checking the dead time plot

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.

Start by locating the Python entry point that opens or displays plots, then compare its current behavior with the CMS total dead-time plot at the linked URL. The change is done when a shifter can open that plot and check whether dead time exceeds 10% across multiple luminosity sections.

Written by the indexing model from the issue text.