Fix SyncSeatLinkRequestWorker license duplication

What does this MR do?

Update SyncSeatLinkRequestWorker: when a new license is created after a successful sync with CustomersDot the old cloud license should be deleted.

Ref issue: https://gitlab.com/gitlab-org/gitlab/-/issues/329447

Screenshots (strongly suggested)

N/A

Does this MR meet the acceptance criteria?

Conformity

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Availability and Testing

• I have added/updated tests following the Testing Guide, or it's not needed. (Consider all test levels. See the Test Planning Process.)
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Security

Does this MR contain changes to processing or storing of credentials or tokens, authorization and authentication methods or other items described in the security review guidelines? If not, then delete this Security section.

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team