Upgrade to Keycloak v25

[megian]

• Rise the minimum Keycloak version to v25.0.6
• Keycloakx Helm Chart to 2.5.1
• Switch the monitoring check from HTTP to HTTPS because the default managment port has HTTPS enabled
• Remove the duplicate --http-enabled parameter as it is already enabled using the environment variable KC_HTTP_ENABLED from the helm chart
• Remove the proxy config and use the default from the helm chart

Checklist

• The PR has a meaningful title. It will be used to auto-generate the
  changelog.
  The PR has a meaningful description that sums up the change. It will be
  linked in the changelog.
• PR contains a single logical change (to build a better changelog).
• Update the documentation.
• Categorize the PR by adding one of the labels:
  bug, enhancement, documentation, change, breaking, dependency
  as they show up in the changelog.
• Link this PR to related issues or PRs.