Originally, crates.io would block on publish requests until the publish
was complete, giving `cargo publish` this behavior by extension.  When
crates.io switched to asynchronous publishing, this intermittently broke
people's workflows when publishing multiple crates.  I say interittent
because it usually works until it doesn't and it is unclear why to the
end user because it will be published by the time they check.  In the
end, callers tend to either put in timeouts (and pray), poll the
server's API, or use `crates-index` crate to poll the index.

This isn't sufficient because
- For any new interested party, this is a pit of failure they'll fall
  into
- crates-index has re-implemented index support incorrectly in the past,
  currently doesn't handle auth, doesn't support `git-cli`, etc.
- None of these previous options work if we were to implement
  workspace-publish support (rust-lang#1169)
- The new sparse registry might increase the publish times, making the
  delay easier to hit manually
- The new sparse registry goes through CDNs so checking the server's API
  might not be sufficient
- Once the sparse registry is available, crates-index users will find
  out when the package is ready in git but it might not be ready through
  the sparse registry because of CDNs

So now `cargo` will block until it sees the package in the index.
- This is checking via the index instead of server APIs in case there
  are propagation delays.  This has the side effect of being noisy
  because of all of the "Updating index" messages.
- This is done unconditionally because cargo used to block and that
  didn't seem to be a problem, blocking by default is the less error
  prone case, and there doesn't seem to be enough justification for a
  "don't block" flag.

The timeout was 5min but I dropped it to 1m.  Unfortunately, I don't
have data from `cargo-release` to know what a reasonable timeout is, so
going ahead and dropping to 60s and assuming anything more is an outage.

Fixes rust-lang#9507