Removed the `replicaCount` option

[CommanderStorm]

Description of the change

In #96 we discussed how replicaCount should work and came to the conclusion that this option is likely misleading. This PR removes this option

Benefits

Currently replicaCount would create a duplicate of the app. Depending on if useDeploy is activated, this could have different consequences, but I dont see a way this has usefull sideeffects. Until uptime-kuma supports sharding/..., this should not be a feature this we offer imo

Possible drawbacks

This feature might have to be reverted in the future, if uptime-kuma supports this someday (it is on the backlog, but it is unclear when this wil come to fruition)

Applicable issues

/

Additional information

Checklist

• [x] Chart version bumped in Chart.yaml according to semver.
• [x] Variables are documented in the README.md

[dirsigler]

Thank you very much and happy Easter holidays! 🐰

[CommanderStorm]

Happy Easter holidays for you too. Thanks for your awesome work ❤️