Based on:
https://answers.atlassian.com/questions/64750/how-to-set-ops-bar-group-size-opsbar-transitions-property-in-jira-config-properties
https://answers.atlassian.com/questions/63782/configuring-the-action-buttons
I am able to tune the number of Workflow buttons via ops.bar.group.size.opsbar-transitions in $JIRA_HOME/jira-config.properties. One problem is that a ghosted "Workflow" dropdown button will appear if the number of transitions available is one less than this value.
But, although my Project is not configured for Greenhopper, I have these silly "Agile Board" and "Rank to Top" buttons which I will never use, prominently placed on my UI. I'd like to get these out of the way. I can not figure a way to configure the button list, but I did try setting ops.bar.group.size.opsbar-operations but I do not observe any change in the number of Operations buttons displayed.

The above screenshot is with jira-config.properties configured like so:
ops.bar.group.size.opsbar-operations = 2
ops.bar.group.size.opsbar-transitions = 4
Jira 5.0.7