Assistance ressource dupe/destruction.

**Describe the bug**
When assisting a building with a large amount of units/buildpower, sometimes mass and energy will either get overused or underused. Instead of using 200 mass and 5000 energy for example, the bug will make the unit be built with 180 mass and 5600 energy. It can also work the opposite way, mainly with game enders (thanks Cheeseberry), where mass will get overpayed. (by a few thousand mass, depending on how much assist was used). This can mainly get problematic in long games when game enders are built with a large amount of units.

**To Reproduce**
Start a sandbox game. Spawn T3 air HQ (cybran), a parangon, an energy storage, and at least 20 hives (upgraded).
Destroy commander. You should have around 300 mass, and 5100 energy. Build the cybran T2 gunship.
The cybran T2 gunships costs 5400 energy. However, you are still able to build it with 5100 energy. If you look at your mass, you will be able to see that you did not use all the mass the unit requiered to build.

**Expected behavior**
Normally, you shouldn't be able to build that gunship with 5100 energy.

**Screenshots**
Here's the replay link, I don't have any screenshots (replay lasts 4 minutes) https://replay.faforever.com/18914442

**Additional context**
With other people on the discord, we made a few theories, it could be from the ressource bar being bugged, build not correctly using ressources at the end of the construction, to the ressources not being used properly among every assist sources.