api(ticdc): fix resign owner cause capture restart bug

[sdojjy]

When API /api/v2/owner/resign was called, cdc capture will restart abnormally.

[asddongmen]

This issue arises when the controller loop exits, triggering the ownerCtx's cancel function. This may cause the owner loop to exit abnormally and return a context canceled error, leading to an unexpected restart of the capture.