Add an extra arg --no-metrics to skip metrics

Bug: 133215912
Test: atest acloud_test
acloud-dev list/create/reconnect/delete --no-metrics

Change-Id: I3fee81abb93e6b5a2e9e709c2101f006b28e859a
diff --git a/metrics/metrics.py b/metrics/metrics.py
index 2a2ae08..b983fc9 100644
--- a/metrics/metrics.py
+++ b/metrics/metrics.py
@@ -16,6 +16,7 @@
 import logging
 
 from acloud.internal import constants
+_NO_METRICS = "--no-metrics"
 
 logger = logging.getLogger(__name__)
 
@@ -35,7 +36,13 @@
 
     Args:
         argv: A list of system arguments.
+
+    Returns:
+        True if start event is sent and need to pair with end event.
     """
+    if _NO_METRICS in argv:
+        return False
+
     try:
         from asuite import atest_utils
         from asuite.metrics import metrics_utils
@@ -43,9 +50,12 @@
         metrics_utils.send_start_event(tool_name=constants.TOOL_NAME,
                                        command_line=' '.join(argv),
                                        test_references=[argv[0]])
+        return True
     except Exception as e:
         logger.debug("Failed to send start event:%s", str(e))
 
+    return False
+
 
 # pylint: disable=broad-except
 def LogExitEvent(exit_code, stacktrace="", logs=""):