By default our HTTP client retries all GET requests. However these post
requests are also idempotent, as we just expect to encrypt/decrypt a
single value, without changing anything on the server side. Retry them,
so network errors won't abort the pulumi program.
There's also some log decryption events that might be retryable, but I'm
not sure about them, so I left them alone for now.
Fixes https://github.com/pulumi/pulumi/issues/15236