Update Vault config to Retry token validation to mitigate "412 required index state not present" errors validating newly created tokens

[richhesk]

Summary

Updates the vault configuration so that it retries token validation to mitigate "412 required index state not present" errors that occur intermittently. The errors seem to result from Vault's eventually consistent approach in a clustered environment which is described at https://developer.hashicorp.com/vault/docs/enterprise/consistency

Types of changes

• Bug fix (non-breaking change which fixes an issue).
• New feature (non-breaking change which adds functionality).
• Breaking change (fix or feature that would cause existing functionality to not work as expected).

Checklist:

• I've added tests for my code.
• My change requires a change or adding to the documentation.
• I have updated the documentation accordingly.