Fixes#32313
OpenTelemetry Tracing
- Added tracing to async task collectors: FlushHostsLastSeen,
collectHostsLastSeen, collectLabelQueryExecutions,
collectPolicyQueryExecutions, collectScheduledQueryStats
- Updated HTTP middleware to use OTEL semantic convention for span names
({method} {route})
- Added OTELEnabled() helper to FleetConfig
Optimizations
- Reduced OTEL batch size from 512 to 256 spans to prevent gRPC message
size errors
- Enabled gzip compression for trace exports
NOTE: I tried to improve OTEL instrumentation for cron jobs, but it got
too complicated due to goroutines in `schedule.go` so that effort should
be separate. We do have SQL instrumentation for cron jobs, but we are
missing root spans for cron jobs as a whole.
# Checklist for submitter
If some of the following don't apply, delete the relevant line.
- [x] Changes file added for user-visible changes in `changes/`,
`orbit/changes/` or `ee/fleetd-chrome/changes`.
## Testing
- [x] QA'd all new/changed functionality manually
<!-- This is an auto-generated comment: release notes by coderabbit.ai
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## Summary by CodeRabbit
* **New Features**
* Expanded OpenTelemetry tracing for async tasks (host last seen, label
membership, policy membership, scheduled query stats) to provide richer
observability.
* More descriptive HTTP span names using “METHOD /route” for clearer
trace analysis.
* **Bug Fixes**
* Improved OTLP gRPC exporter reliability by enabling gzip compression
and reducing export batch size, mitigating intermittent gRPC errors.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
