Update grafana/grafana Docker tag to v8.4.6

This MR contains the following updates:

Package	Type	Update	Change
grafana/grafana	ironbank-docker	minor	8.3.4 -> 8.4.6
grafana/grafana		minor	8.3.4 -> 8.4.6
grafana/grafana	stage	minor	8.3.4 -> 8.4.6

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