Added missing OpenTelemetry instrumentation to several API endpoints. (#32960)

Fixes #32331 

Manually tested all paths. `/test` path removed in
https://github.com/fleetdm/fleet/pull/32962

Also added support for sending errors to OpenTelemetry, like we do for
APM/Sentry.

# Checklist for submitter

- [x] Changes file added for user-visible changes in `changes/`,
`orbit/changes/` or `ee/fleetd-chrome/changes`.
See [Changes
files](https://github.com/fleetdm/fleet/blob/main/docs/Contributing/guides/committing-changes.md#changes-files)
for more information.

## Testing
- [x] QA'd all new/changed functionality manually


<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

* **New Features**
* Added OpenTelemetry tracing across core HTTP endpoints (health,
version, assets, metrics, enroll/root, debug, Apple MDM, SCEP, SCIM)
with dynamic per-request route instrumentation.
* Enhanced error reporting to include OpenTelemetry spans/events with
contextual user/host attributes.

* **Tests**
* Added unit tests validating SCIM and error-handling telemetry, span
naming, and sensitive-data redaction.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

server/service/testing_utils.go

@@ -441,6 +441,7 @@ func RunServerForTestsWithServiceWithDS(t *testing.T, ctx context.Context, ds fl
 				},
 				commander,
 				"https://test-url.com",
+				cfg,
 			)
 			require.NoError(t, err)
 		}
@@ -458,6 +459,7 @@ func RunServerForTestsWithServiceWithDS(t *testing.T, ctx context.Context, ds fl
 				ds,
 				logger,
 				timeout,
+				&cfg,
 			)
 			require.NoError(t, err)
 		}
@@ -479,7 +481,7 @@ func RunServerForTestsWithServiceWithDS(t *testing.T, ctx context.Context, ds fl
 	extra = append(extra, WithLoginRateLimit(throttled.PerMin(1000)))
 
 	if len(opts) > 0 && opts[0].HostIdentity != nil {
-		require.NoError(t, hostidentity.RegisterSCEP(rootMux, opts[0].HostIdentity.SCEPStorage, ds, logger))
+		require.NoError(t, hostidentity.RegisterSCEP(rootMux, opts[0].HostIdentity.SCEPStorage, ds, logger, &cfg))
 		var httpSigVerifier func(http.Handler) http.Handler
 		httpSigVerifier, err := httpsig.Middleware(ds, opts[0].HostIdentity.RequireHTTPMessageSignature, kitlog.With(logger, "component", "http-sig-verifier"))
 		require.NoError(t, err)
@@ -497,7 +499,7 @@ func RunServerForTestsWithServiceWithDS(t *testing.T, ctx context.Context, ds fl
 	rootMux.Handle("/enroll", ServeEndUserEnrollOTA(svc, "", ds, logger))
 
 	if len(opts) > 0 && opts[0].EnableSCIM {
-		require.NoError(t, scim.RegisterSCIM(rootMux, ds, svc, logger))
+		require.NoError(t, scim.RegisterSCIM(rootMux, ds, svc, logger, &cfg))
 		rootMux.Handle("/api/v1/fleet/scim/details", apiHandler)
 		rootMux.Handle("/api/latest/fleet/scim/details", apiHandler)
 	}