[nginx_otel] Dashboard filters accumulate across tab navigation, breaking Request Health

[michaz]

Navigating the tab bar between the three [Nginx OTel] dashboards leaves them broken, because dataset scope is enforced via a removable app-state filter that the Links panel carries over and never clears.

Repro

Open Request Health (works) → Server Internals (works) → back to Request Health → the log panels show no data.

Cause

1. Each dashboard scopes data with a dashboard-level data_stream.dataset filter pill (not inside the Lens queries):
   • Request Health: ∈ {nginx.access.otel, nginx.error.otel, nginxreceiver.otel} (bool-should)
   • Server Internals: = nginxreceiver.otel (match_phrase)
   • Traffic & Capacity: ∈ {nginx.access.otel, nginxreceiver.otel} (bool-should)
2. The tab bar is a Links panel; its dashboard links use the default useCurrentFilters: true, so navigating carries the current filter pills to the destination.
3. Source and destination filters share meta.key = data_stream.dataset but differ in shape (bool-should vs match_phrase), so Kibana stacks them instead of deduping → they get AND-ed together.

Returning to Request Health leaves = nginxreceiver.otel AND ∈ {access, error, nginxreceiver}, whose intersection is nginxreceiver.otel only. Request Health's panels query the nginx.access / nginx.error log datasets, so they now match nothing. Server Internals masks the bug because its panels are the nginxreceiver metrics.

Confirmed against packages/nginx_otel/kibana/dashboard/*.json on main.

Suggested fix

• Scope each Lens layer by dataset in its own query, rather than relying on a removable app-state filter; and/or
• Set useCurrentFilters: false on the Links panel's dashboard links so navigation doesn't carry filters over.