Report time of applying experiments as a single sample to Glean

This happens early during startup and Glean will now delay executing the
actual recording until after libxul is loaded externally.
This avoids forcing that load of Glean/libxul too early.

components/nimbus/android/src/main/java/org/mozilla/experiments/nimbus/Nimbus.kt

@@ -44,6 +44,7 @@ import org.mozilla.experiments.nimbus.internal.NimbusException
 import org.mozilla.experiments.nimbus.internal.RecordedContext
 import java.io.File
 import java.io.IOException
+import kotlin.system.measureTimeMillis
 
 private const val EXPERIMENT_COLLECTION_NAME = "nimbus-mobile-experiments"
 private const val NIMBUS_DATA_DIR: String = "nimbus_data"
@@ -308,10 +309,12 @@ open class Nimbus(
     @VisibleForTesting(otherwise = VisibleForTesting.PRIVATE)
     internal fun applyPendingExperimentsOnThisThread() = withCatchAll("applyPendingExperiments") {
         try {
-            val events = NimbusHealth.applyPendingExperimentsTime.measure {
-                nimbusClient.applyPendingExperiments()
+            var events: List<EnrollmentChangeEvent>?
+            val time = measureTimeMillis {
+                events = nimbusClient.applyPendingExperiments()
             }
-            recordExperimentTelemetryEvents(events)
+            NimbusHealth.applyPendingExperimentsTime.accumulateSingleSample(time)
+            recordExperimentTelemetryEvents(events!!)
             // Get the experiments to record in telemetry
             postEnrolmentCalculation()
         } catch (e: NimbusException.InvalidExperimentFormat) {