The `tidy` parameter is buggy, and ignores all ordering
metaparameters. This is fixed in Puppet 7[^1], but it's helpful to
resolve it now. Specifically, this fixes bugs with tidy running too
early, and deleting the old version of a package before its new
version is installed or symlinked, leaving a race condition if
anything tries to run the binary in this window.
This is mostly not a problem for Supervisor-managed processes, since
the binary is already running, and can continue to run if it is tidied
out from under the running process. For stand-alone tools like wal-g,
which are run frequently by PostgreSQL, this may cause issues if
PostgreSQL tries to call them during a puppet run.
Remove all complicated uses of tidy, and replace them with an `exec`
which does the equivalent. We also generate `file` resources for
binaries, making them easier (and clearer) to specify as dependencies.
[^1]: https://puppet.atlassian.net/browse/PUP-10688
We require a `pg_dump` whose version matches the version of the server
we are configured against (see 3a8b4b0205). Installing the latest
`postgresql-client` does not guarantee that we have such a binary
present.
