fix: keepalived weights and slave naming

[gseidel]

According to https://manpages.debian.org/testing/keepalived/keepalived.conf.5.en.html

(b) vrrp tracking scripts that will cause vrrp instances to go down it they exit a 
non-zero exist status, or if a weight is specified will add or subtract
the weight to/from the priority of that vrrp instance.

Means if the master priortiy is 200 and vrrp weight is 101 ...
and vrrp succeed, the master priortiy is 301
and vrrp fails, the master priortiy is 200

The backup is always 100, so it will never failover!

Guess the weight should be -101 so the priority get 99 and is below 100.

On the other hand, the docs and also the logs always talking about the backup daemon and never about slave, so I changed the namings as well.

[svenja11]

Thank you for the update @gseidel!

Please add this comment to this PR, and I will merge it (remember to replace YOUR NAME <[email protected]> with your own information):

I have read and understood the Contributor's Certificate of Origin available at the end of
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[gseidel]

@svenja11 You are welcome.

I have read and understood the Contributor's Certificate of Origin available at the end of
https://raw.githubusercontent.com/hetzneronline/community-content/master/tutorial-template.md
and I hereby certify that I meet the contribution criteria described in it.
Signed-off-by: Gerhard Seidel [email protected]