Load test pub server

[munificent]

We should do some testing to ensure pub.dartlang.org can handle reasonable server loads. There is internal documentation on how to do this.

[munificent]

Removed this from the M1 milestone.
Added this to the M2 milestone.

[munificent]

Removed the owner.

[munificent]

Removed Type-Defect label.
Added Type-Task label.

[munificent]

We've launched, so we've done a real world load test at this point.

---

Added WontFix label.

[DartBot]

This issue has been moved to dart-lang/pub#68.