tests: adjust testCreateStoragePools to remove each created pool after creating it
tests: adjust testCreateStoragePools to remove each created pool after creating it

This will allow us to reuse same sources for different pools in the
test.

moraleslazaro/cockpit,mvollmer/cockpit,cockpituous/cockpit,moraleslazaro/cockpit,garrett/cockpit,cockpituous/cockpit,cockpit-project/cockpit,garrett/cockpit,martinpitt/cockpit,moraleslazaro/cockpit,martinpitt/cockpit,cockpit-project/cockpit,moraleslazaro/cockpit,garrett/cockpit,garrett/cockpit,mvollmer/cockpit,cockpituous/cockpit,cockpit-project/cockpit,deryni/cockpit,mvollmer/cockpit,garrett/cockpit,martinpitt/cockpit,deryni/cockpit,deryni/cockpit,mvollmer/cockpit,cockpit-project/cockpit,mvollmer/cockpit,cockpituous/cockpit,moraleslazaro/cockpit,cockpituous/cockpit,cockpit-project/cockpit,moraleslazaro/cockpit,cockpituous/cockpit,martinpitt/cockpit,deryni/cockpit,deryni/cockpit,martinpitt/cockpit,deryni/cockpit,deryni/cockpit,moraleslazaro/cockpit