Set template-generate throttle parameter dynamically/automatically

[anngvu]

Currently, each time we add or remove templates that should be generated during tests, the test script has to fiddle around with the throttle parameter to account for API rate limits. This part should just be "smarter" so that it's easier for others (re)use this script. (For example, someone on our team adds a template and forgets to update this -- it should be one less thing to think about.)