When having Aghanim's Scepter, Freezing Field applies Frostbite on enemies who are affected for 2.5 seconds.

These Frostbites always use the hero duration, despite the Frostbite spell having a creep duration for non-ancient creeps.

Repro:
1. Get Aghanim's Scepter
2. Have 2 enemy Centaur Conquerors dominated by Chen with 2000 creep hp talent
3. Cast Frostbite on one of the Centaurs
4. Immediately start channeling Freezing Field so that the 2nd centaur is within the area
5. Wait for the Frostbite to apply
6. Cancel Freezing Field
7. Check which Frostbite expirers first

Result: The frostbite applied by Freezing Field expires first, despite it being applied at least ~3 seconds after the manually cast Frostbite. Freezing Field used the hero duration on the creep.

Expected: Freezing Field should use the creep duration (10 seconds, 11.5 with talent) on non-ancient creeps, just like how a manually cast Frostbite does.