Dec 2022 Fulfillment error budget report - Investigate requests and job executions

The December 2022 Error Budget report came out (see related issue) and the following numbers for Fulfillment came out:

Product Stage	Stage Group	Dec 2022 Error Budget	Nov 2022 Error Budget
fulfillment	billing_and_subscription_management	89.47	94.64
fulfillment	commerce_integrations	92.06	90.34
fulfillment	fulfillment_platform	90.32	99.62
fulfillment	provision	71.90	78.97
fulfillment	purchase	98.43	99.85
fulfillment	utilization	99.98	99.98

One option to explore that will lead to some improvement is iterating over the introduction of the "urgency" class attribute:

• as @lulalala pointed out in this comment, the default Apdex threshold for GitLab is 1 second, whereas we still have it set to 400ms for CustomersDot. If there is no particular reason why we should not raise that bar, I'd be in favor of also having 1 second as an Apdex default for CustomersDot.

This issue serves also as a follow-up of #5119 (closed)