provider/azure: make boilerplate <> usage consistent

Remove <> from boilerplate values for consistency's
sake, to reduce confusion about what needs replacing.
This matches the docs.

Fixes https://bugs.launchpad.net/juju-core/+bug/1381289
Merge pull request #1015 from axw/lp1381289-azure-boilerplate-consistency

provider/azure: make boilerplate <> usage consistent

Remove <> from boilerplate values for consistency's
sake, to reduce confusion about what needs replacing.
This matches the docs.

Fixes https://bugs.launchpad.net/juju-core/+bug/1381289