Move leases RBAC to *-metadata-reader role when HA is enabled

[Eykha]

Fixes #950.

Logs from the standby pod:

[...]
I0305 18:22:06.110079       1 leaderelection.go:258] "Attempting to acquire leader lease..." lock="default/stakater-reloader-lock"
time="2026-03-05T18:22:06Z" level=info msg="Meta info configmap already exists, updating it"
E0305 18:22:06.126553       1 leaderelection.go:456] "Error initially creating lease lock" err="leases.coordination.k8s.io \"stakater-reloader-lock\" already exists" lock="default/stakater-reloader-lock"
time="2026-03-05T18:22:09Z" level=info msg="new leader is reloader-reloader-7856b75b8-f9npn"
[Killed leader here]
I0305 18:27:43.437656       1 leaderelection.go:272] "Successfully acquired lease" lock="default/stakater-reloader-lock"
time="2026-03-05T18:27:43Z" level=info msg="became leader, starting controllers"
time="2026-03-05T18:27:43Z" level=info msg="still the leader!"
[...]