add skip/docker alias to skip tests when running on Docker (#45955)

* add skip/docker alias to skip tests when running on Docker

* changed warning message wording

test/integration/targets/xattr/aliases

@@ -1,4 +1,5 @@
 shippable/posix/group2
+skip/docker
 skip/freebsd
 skip/osx
 destructive

test/runner/lib/executor.py

@@ -1441,6 +1441,13 @@ def get_integration_docker_filter(args, targets):
 
     common_integration_filter(args, targets, exclude)
 
+    skip = 'skip/docker/'
+    skipped = [target.name for target in targets if skip in target.aliases]
+    if skipped:
+        exclude.append(skip)
+        display.warning('Excluding tests marked "%s" which cannot run under docker: %s'
+                        % (skip.rstrip('/'), ', '.join(skipped)))
+
     if not args.docker_privileged:
         skip = 'needs/privileged/'
         skipped = [target.name for target in targets if skip in target.aliases]