Lowers the budget cost of Clings/Vampires

[Erikos66]

What Does This PR Do

Decreases the budget cost of changelings and vampires from 10 -> 8.

Why It's Good For The Game

Every shift I've had on the ruleset of Cling/Vampire has led to a low number of either type of antag, usually 3 and sometimes 4 total during high-pop hours. Between newer players, the stealth of these antags and antags having each other as targets lead to little to no antag activity for these rounds.

The aim of this is to have an average antag count of 5 for this ruleset, bringing it more in-line with other rulesets.

It only adjusts the cost of each antag, not the amount per pop that can be purchased, lower population count will remain unaffected. Especially if combined with #28300

Testing

Local server builds and runs, would needed to be tested on live to see the full results. TM was advised due to being antag changes, and the possibility of affecting lower population hours.

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Declaration

• I confirm that I either do not require pre-approval for this PR, or I have obtained such approval and have included a screenshot to demonstrate this below.

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tweak: Reduces the cost of clings/vampire from 10->8
/:cl: