Add exclusion for fleet-agent for backup restore

[mmartin24]

Related to https://github.com/rancher/backup-restore-operator/issues/532

While testing Backup restore, it seemed it was not beneficial to backup the fleet-agent

[manno]

This could be better in 0.10, as the fleet-agent is a statefulset and not included in the backed up resources.

[mmartin24]

Retested in Rancher 2.9 with fleet 0.10 and the same issue is observed where statefulset is not backed up (logs can be found here ) so not sure if it makes sense to continue this issue.