(#7879) Update the container version in pool.yaml file to 8.9.8
(#7879) Update the container version in pool.yaml file to 8.9.8

We are not planning to rebuild the 8.9.6 containers with the UID/GID
change, only the 8.9.8 containers, so pool.yaml needs to use the 8.9.8
containers.

htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor