fix(monitoring): make VPCSC env comparison case-insensitive (#9564)

Author: steinwaywhw

monitoring/noxfile.py

@@ -122,7 +122,8 @@ def system(session):
     session.install("-e", ".")
 
     # Additional setup for VPCSC system tests
-    if os.environ.get("GOOGLE_CLOUD_TESTS_IN_VPCSC") != "true":
+    in_vpc = os.environ.get("GOOGLE_CLOUD_TESTS_IN_VPCSC", "false")
+    if in_vpc.lower() != "true":
         # Unset PROJECT_ID, since VPCSC system tests expect this to be a project
         # within the VPCSC perimeter.
         env = {