TriggerJobOpts: refactor EDMVersion flag
Move the code to discover the EDMVersion
flag in bytestream files to
TrigEDMConfig.Utils
and cache the result for a given bytestream file.
This ensures we are only reading the file once. This is especially
important for mixed old/new job options where the flags are not being
locked and hence this function is called every time code reads the
EDMVersion
flag.
cc @rbielski