Solve extra warnings that was confusing the user

Q1D2: correct the warning message to have WorkspaceIndex.

SANSRunWindow:
  * warning user that we will ignore the FLOOD file option when
the detector is the FRONT/HAB detector. A new ticket will be opened to deal
with this properly.
  * Skip reloading the user file for every single reduction that caused
extra warnings to appear, confusing the user.
  * Accept DET/MERGE option to be passed as well as DET/MERGED.

ISISCommandInterface-> temporaly clear the FloodFile when reducting the FRONT/HAB detector.

re #5844