[REFACTOR] Updates Vampire strain code, fixes missing headbite cooldown and early DEAD target check.

[Venuska1117]

Detached from: #12601

About the pull request

Updates abilities code, fixes vampire headbite lacking checks for cooldown and if target is DEAD.

Explain why it's good for the game

Cleaner code, easier to follow, fixing issues.

Testing Procedure

Made new code, run code, no errors.
spawn vampire, use abilities, abilities work fine.
use headbite, headbite cannot attack on cooldown.
use headbite on dead target, ability stops instantly instead of after delay.

Code works as intended.

Changelog

🆑 Venuska1117
refactor: Updates Vampire code for cleaner look and making it easier to follow.
fix: Added missing cooldown check on vampire headbite and early return check if target is DEAD.
/:cl:

[cmss13-ci]

This PR has been inactive for long enough to be automatically marked as stale. This means it is at risk of being auto closed in ~ 7 days, please address any outstanding review items and ensure your PR is finished, if these are all true and you are auto-staled anyway, you need to actively ask maintainers if your PR will be merged. Once you have done any of the previous actions then you should request a maintainer remove the stale label on your PR, to reset the stale timer. If you feel no maintainer will respond in that time, you may wish to close this PR youself, while you seek maintainer comment, as you will then be able to reopen the PR yourself

[cmss13-ci]

This PR has been inactive for long enough to be automatically marked as stale. This means it is at risk of being auto closed in ~ 7 days, please address any outstanding review items and ensure your PR is finished, if these are all true and you are auto-staled anyway, you need to actively ask maintainers if your PR will be merged. Once you have done any of the previous actions then you should request a maintainer remove the stale label on your PR, to reset the stale timer. If you feel no maintainer will respond in that time, you may wish to close this PR youself, while you seek maintainer comment, as you will then be able to reopen the PR yourself