Fix mistake in fixture count metrics
Fix mistake in fixture count metrics

Three variables were getting set to the same empty list
instead of to different empty lists as intended.
This appears to have only affected the metric values themselves
incidentally, which is why tests didn't catch it.

dimagi/commcare-hq,dimagi/commcare-hq,dimagi/commcare-hq,dimagi/commcare-hq,dimagi/commcare-hq