automation: wait for instance profiles and roles
Otherwise there is a race condition between creating the resources
and us attempting to use them / them becoming available.
The role waiter API was recently introduced, so we had to upgrade
the boto3 package to get it. Other packages were also updated
to latest versions just because.
Even with this change, I still run into issues with the IAM instance
profile not being available when we attempt to create an EC2 instance
using a just-created profile. I'm not sure what's going on. Possibly
a bug on Amazon's end. But the new behavior is "more correct."
Differential Revision: https://phab.mercurial-scm.org/D6286