Backport of PKI: Track last time auto tidy was run across restarts into release/1.18.x

[hc-github-team-secure-vault-core]

Backport

This PR is auto-generated from #28488 to be assessed for backporting due to the inclusion of the label backport/1.18.x.

The below text is copied from the body of the original PR.

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Description

Start persisting the last time we ran auto-tidy in order to not lose the information across restarts. If an auto-tidy schedule was set to run every 7 days, but there was a scheduled Vault restart every 6 days, auto-tidy would never run as the counter would be reset on restart.

We add in two new auto-tidy fields to control a possible thundering herd problem of having too many auto-tidy processes starting up at once. min_startup_backoff_duration and max_startup_backoff_duration fields with defaults of 5m and 15m respectively.

The UI for auto-tidy has been updated, adding the two new fields to the auto-tidy configuration screen, the new fields are hidden if not enabled, as well as being displayed within the auto-tidy configuration view. They do not appear on the manual tidy screens.

TODO only if you're a HashiCorp employee

• Backport Labels: If this PR is in the ENT repo and needs to be backported, backport
  to N, N-1, and N-2, using the backport/ent/x.x.x+ent labels. If this PR is in the CE repo, you should only backport to N, using the backport/x.x.x label, not the enterprise labels.
  • If this fixes a critical security vulnerability or severity 1 bug, it will also need to be backported to the current LTS versions of Vault. To ensure this, use all available enterprise labels.
• ENT Breakage: If this PR either 1) removes a public function OR 2) changes the signature
  of a public function, even if that change is in a CE file, double check that
  applying the patch for this PR to the ENT repo and running tests doesn't
  break any tests. Sometimes ENT only tests rely on public functions in CE
  files.
• Jira: If this change has an associated Jira, it's referenced either
  in the PR description, commit message, or branch name.
• RFC: If this change has an associated RFC, please link it in the description.
• ENT PR: If this change has an associated ENT PR, please link it in the
  description. Also, make sure the changelog is in this PR, not in your ENT PR.

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Overview of commits

• 2db2a9f

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