Keycloak missing required Arg in values.yaml

Description

The "start" argument was removed from the Keycloak package chart/values.yaml during the last renovate update. This MR adds the argument back in. Issue was reported by community member: https://bigbanguniver-ft39451.slack.com/archives/C051A2BPS0K/p1722513376742349

Fix

• Add the "start" argument back