Backport of Fix vault path-help for selected paths with bad regexps into release/1.13.x

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

Backport

This PR is auto-generated from #18571 to be assessed for backporting due to the inclusion of the label backport/1.13.x.

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

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Describe the bug
When a Vault API path has been defined with a regex that requires a final slash, the vault path-help command is unable to retrieve help for it.

Underlying cause
Vault's code automatically appends a trailing slash on to all paths used for ListOperations, but removes a trailing slash for all other operations, including HelpOperations. In order for a path pattern to match both ListOperation and HelpOperation, it must accept both the presence and absence of a trailing slash.

To Reproduce, or test the fix

1. Start a Vault dev server
2. Run vault path-help auth/token/accessors/
3. See an unsupported path error

Expected behavior
Help message displayed as expected.

Fix
Update the few path regex patterns that fall into this trap to end with /? instead of /.

Update a comment to explain why.

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Overview of commits

• 2f67766

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