www/grafana9: update to 9.5.15
Changelog:
- https://github.com/grafana/grafana/releases/tag/v9.5.15
- https://github.com/grafana/grafana/releases/tag/v9.5.14
- https://github.com/grafana/grafana/releases/tag/v9.5.13
- https://github.com/grafana/grafana/releases/tag/v9.5.12
- https://github.com/grafana/grafana/releases/tag/v9.5.10
- https://github.com/grafana/grafana/releases/tag/v9.5.9
- https://github.com/grafana/grafana/releases/tag/v9.5.8
PR: 275433