Add vehicle dff leak fix back

[ghost]

The model unload crash was fixed in PR #1623. I disabled 2 lines of code there:

m_pDFFManager->RestoreModel(usModelID);

and

CTxdStore_RemoveRef(pModelInfoInterface->usTextureDictionary);

The problem was CTxdStore_RemoveRef. I added this line because I thought MTA was not clearing texture references, but it turns out that someone added a fix for this problem somewhere in code, so this caused the problems with the texture references. This line of code is not needed there because there's already a fix somewhere in MTA, and we can remove it. This means we can restore the DFF leak fix, which is this line:

m_pDFFManager->RestoreModel(usModelID);