storage: pool: Fix handling of errors on pool lookup failure

storage: pool: Fix handling of errors on pool lookup failure

Rework internal pool lookup code to avoid printing the raw UUID buffer
in the case a storage pool can't be found:

 $ virsh pool-name e012ace0-0460-5810-39ef-1bce5fa5a4dd
 error: failed to get pool 'e012ace0-0460-5810-39ef-1bce5fa5a4dd'
 error: Storage pool not found: no storage pool with matching uuid à¬à`X9ï_¥¤Ý

The rework is mostly done by switching the lookup code to the newly
introduced helper virStoragePoolObjFromStoragePool

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1104993