Bastion/DoubleDragon: do not remove blackout timer on debuff removal

[stako]

For the Theralion & Valiona boss fight in Cataclysm's Bastion of Twilight raid:

• When the Blackout debuff is applied to a unit, the Blackout timer is correctly reset to 45 seconds.
• When the same Blackout debuff is removed, the timer incorrectly is also removed - now we don't have a timer for the next Blackout.
• Blackout timer should only be removed when entering the "Theralion on ground" phase.

Video demonstrating the issue
The BigWigs timers are in grey & white on the left side of the screen. The blue timers are from a different addon.

[funkydude]

Thanks!