An ACU death explosion gives veterancy resulting from friendly unit deaths to enemy ACUs before the explosion damage is applied

**Describe the bug**
An ACU death explosion gives veterancy resulting from friendly unit deaths to enemy ACUs before the explosion damage is applied. This can allow an enemy with less than 2500 HP ACU in range of an ACU explosion to survive, when it should have died.

This bug is reminiscent of a similar bug from last year, #4750, but distinct in that non-ACU units need to be present to trigger it. The bug described in #4750 remains fixed. (Quickly tested here: [#21977005](https://replay.faforever.com/21977005))

**To Reproduce**
I learned about it first in a tournament game played by sladow, where he ctrl+k's to secure the win, which fails due to this bug: https://youtu.be/I6ZeTOMh6sE?si=izYE6JcpO22CwbCf&t=1035

To reproduce, damage a couple units with ACU A, enough that, were they to be killed, they'd give a veterancy level to ACU A. Then have ACU B in range of both ACU A and those damage units, while ACU A is slightly below 2500 HP. Ctrl+K ACU B and ACU A will survive due to the vet gained __

This is done in this test replay (min 2-5), where I damage a couple sniperbots, which then give me the health to survive the enemy ACU explosion: [#21976639](https://replay.faforever.com/21976639)

Notably, the ctrl+k is not required. If the ACU dies normally, from being shot, the same bug happens. Reproduced in this test game: [#21977078](https://replay.faforever.com/21977078)

**Expected behavior**
An ACU with less than 2500 HP in range of an ACU explosion should always die, no exceptions.

Preferably, this would also be true for chain explosions. So an ACU with 7500 HP, in range of a first exploding ACU, who kills a second ACU with 2500 HP who together kill a third ACU with 5000 HP, would also always die, regardless of any veterancy calculations.