Backport of Fix bug with Vault CA provider into release/1.15.x

[hc-github-team-consul-core]

Backport

This PR is auto-generated from #18112 to be assessed for backporting due to the inclusion of the label backport/1.15.

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The person who merged in the original PR is:
@kisunji
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The below text is copied from the body of the original PR.

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Background for reviewers

Vault can be used as a CA for Consul service mesh (docs). Typically an organization's root trust CA is stored as a root mount (configured by RootPKIPath) in Vault. Consul uses an intermediate CA (stored in IntermediatePKIPath) signed by the root to issue leaf certificates to agents and services in the mesh.

Description

Updating RootPKIPath but not IntermediatePKIPath would not update leaf signing certs with the new root. Unsure if this happens in practice but manual testing showed it is a bug that would break mesh and agent connections once the old root is pruned.

Testing & Reproduction steps

Added a unit test case updating RootPKIPath and not IntermediatePKIPath

Manually tested with a local cluster to ensure updating RootPKIPath did not break mesh communication.

PR Checklist

• updated test coverage
• external facing docs updated
• appropriate backport labels added
• not a security concern

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Overview of commits

• 57bb6f3 - b2dad88 - 753d3c0

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[github-team-consul-core-pr-approver]

Auto approved Consul Bot automated PR

[kisunji]

No need here. 1.15.x did not have the refactors