[VPA] Support leader election for recommender

[libfitz]

Is your feature request related to a problem? Please describe.
Installing the recommender with leader-elect: true does not work at the moment because vpa-status-reader-binding only includes the updater service account.

Describe the solution you'd like
vpa-status-reader-binding should optionally include the recommender service account, allowing operators to run recommender with ≥2 replicas.

[sudermanjr]

Please feel free to open a PR for this functionality. Thanks.