Add rprivate to CDI mount options

This ensures that mount propagation is set to rprivate for
mounts from the host into the container. This aligns with the
default in docker.

Signed-off-by: Evan Lezar <elezar@nvidia.com>

cmd/nvidia-ctk-installer/toolkit/toolkit_test.go

@@ -109,7 +109,8 @@ containerEdits:
             - ro
             - nosuid
             - nodev
-            - bind
+            - rbind
+            - rprivate
 `,
 		},
 	}

cmd/nvidia-ctk/cdi/generate/generate_test.go

@@ -111,7 +111,8 @@ containerEdits:
             - ro
             - nosuid
             - nodev
-            - bind
+            - rbind
+            - rprivate
 `,
 		},
 	}