For other test cases, the operator is going to produce similar generated
objects in several codepaths, and those objects are large. Move them out
to helpers so that the main test code stays a bit more intelligible.
The top-level Service that we start and end with remains in the main test
body, because its shape at the start and end is one of the main things that
varies a lot between test cases.
Updates #502.
Signed-off-by: David Anderson <danderson@tailscale.com>
