Backport of Cache trusted cert values, invalidating when anything changes into release/1.15.x

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

Backport

This PR is auto-generated from #25421 to be assessed for backporting due to the inclusion of the label backport/1.15.x.

🚨

Warning automatic cherry-pick of commits failed. If the first commit failed,
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The person who merged in the original PR is:
@sgmiller
This person should manually cherry-pick the original PR into a new backport PR,
and close this one when the manual backport PR is merged in.

merge conflict error: POST https://api.github.com/repos/hashicorp/vault/merges: 409 Merge conflict []

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

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Previously, trusted certs were loaded and parsed on every login call. This
is both slow, and means a copy of the trusted certs is in memory per login.
For highly concurrent use this raises Vault's memory usage unnecessarily.

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Overview of commits

• 734afbe

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CI Results:
All Go tests succeeded! ✅