www/grafana7: Update to 7.5.10 and unbreak build

Changes since 7.5.6:

• Dockerfile: Fixes missing -no-cache.
• Annotations: Prevent orphaned annotation tags cleanup when no annotations were cleaned.
• Quota: Do not count folders towards dashboard quota.
• Datasource: Add support for max_conns_per_host in dataproxy settings.
• Datasource: Add support for max_idle_connections_per_host in dataproxy settings.
• Instrumentation: Add metrics for outbound HTTP connections.
• Snapshots: Remove dashboard links from dashboard snapshots.
• Fix Unauthorized message that is displayed on sign-in or snapshot page.
• Transformations: add `prepare time series' transformer.

PR: 258134
Reported by: Fredrik Eriksson
Approved by: robsonmantovani@gmail.com (maintainer timeout, 2 weeks)