Work around blizzard delves event bug

[ynazar1]

In 11.0.2 while in delves the event GROUP_ROSTER_UPDATE constantly triggers causing addon to recalculate buffs

https://us.forums.blizzard.com/en/wow/t/an-event-called-grouprosterupdate-appears-to-be-constantly-firing/1940551

This causes constant stutter due to cost of redoing all the calls every second.
smartbuff.lua line 706 or so:

  if event == "ZONE_CHANGED_NEW_AREA" or event == "GROUP_ROSTER_UPDATE" then
    SMARTBUFF_SetTemplate()
  end

[ynazar1]

Putting a workaround to get it to not spam template refresh during delves. I'm not super happy about this but this is kinda of a hack around a bug. This could have some unintended consequences if group changes during a scenario but those are rare edge cases i imagine.

  -- TODO: This is a blizzard bug workaround that spams GROUP_ROSTER_UPDATE during delves
  local name, instanceType, difficultyID, difficultyName, maxPlayers, dynamicDifficulty, isDynamic, instanceID, instanceGroupSize, LfgDungeonID =
  GetInstanceInfo()
  if event == "ZONE_CHANGED_NEW_AREA" or (event == "GROUP_ROSTER_UPDATE" and instanceType ~= "scenario") then
    SMARTBUFF_SetTemplate()
  end