[bug 1103167] Raise GET API throttle

This raises the throttle to 200ph.

Note: This is another arbitrarily chosen number, but this one is larger
than the previously arbitrarily chosen number. Next time we think about
raising it, we should look at usage patterns.
Merge pull request #396 from willkg/1103167-raise-throttle

[bug 1103167] Raise GET API throttle