Update registry1.dso.mil/ironbank/hashicorp/vault Docker tag to v1.15.3

This MR contains the following updates:

Package	Update	Change
registry1.dso.mil/ironbank/hashicorp/vault (source)	minor	1.14.10 -> 1.15.3
registry1.dso.mil/ironbank/hashicorp/vault-csi-provider (source)	patch	v1.4.2 -> v1.4.3

---

Configuration

📅 Schedule: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined).

🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.

♻ Rebasing: Whenever MR becomes conflicted, or you tick the rebase/retry checkbox.

👻 Immortal: This MR will be recreated if closed unmerged. Get config help if that's undesired.

---

• If you want to rebase/retry this MR, check this box

---

This MR has been generated by Renovate Bot

Upgrade Notices

• In the new upgraded Vault version (1.15.3) "Secret Engines" is now "Secrets engines" with a lower case "e" which initially failed the Cypress-test because "Secret Engines" could not be found.
• The generate random token Cypress-Test was also failing due to letter cases. Random bytes was changed to "Random Bytes" in the test script to be able to generate random token.