Add ability to update authentication token for pull mirroring without recreating configuration

Problem

When a token used for pull mirroring expires, customers cannot update or replace the expired token with a new one. Instead, they must:

1. Delete the entire pull mirroring configuration
2. Recreate the mirroring setup from scratch

This creates significant operational overhead for customers who manage many mirrors with tokens that expire regularly (typically annually).

Proposal

Add the ability to update/replace the authentication token for an existing pull mirror configuration without requiring deletion and recreation of the entire setup.

Benefits

• Reduces operational overhead for customers managing multiple mirrors
• Prevents potential downtime or gaps in mirroring during token rotation
• Improves user experience for token lifecycle management
• Aligns with security best practices for regular token rotation

Use Case

Customers with numerous pull mirrors that use token-based authentication need to rotate tokens on a regular basis (e.g., annual expiration policies). The current workflow is time-consuming and error-prone when managing many mirrors.