tests/cl.filesystem: skip "/run", fix test failure on arm64

On arm64, we have a `/run/udev/data/+platform:Fixed MDIO bus.0`, which
gets flagged due to the presence of spaces in the filename. Since /run
is an ephemeral directory and we skip other directories (/proc, /sys)
for that reason, it seems like a good idea to skip /run as well.

kola/tests/misc/files.go

@@ -181,6 +181,7 @@ func Blacklist(c cluster.TestCluster) {
 		"/sys",
 		"/var/lib/docker",
 		"/var/lib/rkt",
+		"/run",
 	}
 
 	blacklist := []string{