Drop redundant lib/oslo

It was kept for compatibility in renaming which was merged long ago[1],
and is no longer necessary.

[1] 3ed99c0b27122ff00e2d236086ab16b0cc1887c1

Depends-on: https://review.opendev.org/c/openstack/grenade/+/936095
Change-Id: I6a66359c19d0385beafb4c5e57b6ec3cd6d9cc54
diff --git a/clean.sh b/clean.sh
index 6a31cc6..092f557 100755
--- a/clean.sh
+++ b/clean.sh
@@ -40,7 +40,7 @@
 
 source $TOP_DIR/lib/tls
 
-source $TOP_DIR/lib/oslo
+source $TOP_DIR/lib/libraries
 source $TOP_DIR/lib/lvm
 source $TOP_DIR/lib/horizon
 source $TOP_DIR/lib/keystone