auth/userpass: update dummy string

[mickael-hc]

Description

Updates the user pass dummy string, see https://github.com/hashicorp/vault-enterprise/pull/8418

TODO only if you're a HashiCorp employee

• Backport Labels: If this fix needs to be backported, use the appropriate backport/ label that matches the desired release branch. Note that in the CE repo, the latest release branch will look like backport/x.x.x, but older release branches will be backport/ent/x.x.x+ent.

  • LTS: 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 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.

PCI review checklist

• I have documented a clear reason for, and description of, the change I am making.
• If applicable, I've documented a plan to revert these changes if they require more than reverting the pull request.
• If applicable, I've documented the impact of any changes to security controls.

Examples of changes to security controls include using new access control methods, adding or removing logging pipelines, etc.

[github-actions]

Build Results:
All builds succeeded! ✅

[github-actions]

CI Results:
All required Go tests succeeded but failures were detected ⚠️
Failures:

Test Type	Package	Test	Logs