Addressed code review comments

Author: anush-apple

src/darwin/Framework/CHIP/MTRDevice.mm

@@ -1177,8 +1177,6 @@ - (void)_handleSubscriptionEstablished
 {
     os_unfair_lock_lock(&self->_lock);
 
-    MATTER_LOG_METRIC_END(kMetricMTRDeviceSubscriptionSetup, CHIP_NO_ERROR);
-
     // We have completed the subscription work - remove from the subscription pool.
     [self _clearSubscriptionPoolWork];
 
@@ -1187,6 +1185,7 @@ - (void)_handleSubscriptionEstablished
     if (HadSubscriptionEstablishedOnce(_internalDeviceState)) {
         [self _changeInternalState:MTRInternalDeviceStateLaterSubscriptionEstablished];
     } else {
+        MATTER_LOG_METRIC_END(kMetricMTRDeviceInitialSubscriptionSetup, CHIP_NO_ERROR);
         [self _changeInternalState:MTRInternalDeviceStateInitialSubscriptionEstablished];
     }
 
@@ -1227,8 +1226,6 @@ - (void)_handleSubscriptionError:(NSError *)error
 {
     std::lock_guard lock(_lock);
 
-    MATTER_LOG_METRIC_END(kMetricMTRDeviceSubscriptionSetup, [MTRError errorToCHIPErrorCode:error]);
-
     [self _changeInternalState:MTRInternalDeviceStateUnsubscribed];
     _unreportedEvents = nil;
 
@@ -2345,7 +2342,9 @@ - (void)_setupSubscriptionWithReason:(NSString *)reason
         });
     }
 
-    MATTER_LOG_METRIC_BEGIN(kMetricMTRDeviceSubscriptionSetup);
+    // This marks begin of initial subscription to the device (before CASE is established). The end is only marked after successfully setting
+    // up the subscription since it is always retried as long as the MTRDevice is kept running.
+    MATTER_LOG_METRIC_BEGIN(kMetricMTRDeviceInitialSubscriptionSetup);
 
     // Call directlyGetSessionForNode because the subscription setup already goes through the subscription pool queue
     [_deviceController

src/darwin/Framework/CHIP/MTRMetricKeys.h

@@ -88,8 +88,8 @@ constexpr Tracing::MetricKey kMetricBLEDevicesRemoved = "dwnfw_ble_devices_remov
 // Unexpected C quality attribute update outside of priming
 constexpr Tracing::MetricKey kMetricUnexpectedCQualityUpdate = "dwnpm_bad_c_attr_update";
 
-// Subscription setup from darwin MTRDevice
-constexpr Tracing::MetricKey kMetricMTRDeviceSubscriptionSetup = "dwnpm_dev_subscription_setup";
+// Setup from darwin MTRDevice for initial subscrption to a device
+constexpr Tracing::MetricKey kMetricMTRDeviceInitialSubscriptionSetup = "dwnpm_dev_initial_subscription_setup";
 
 } // namespace DarwinFramework
 } // namespace Tracing