[Enhancement] Assign offset in offsetTable even if the subscriptio not exist.

[dingshuangxi888]

Before Creating the Enhancement Request

• I have confirmed that this should be classified as an enhancement rather than a bug/feature.

Summary

Assign offset in offsetTable even if the subscription key not exist for reset offset API.

Motivation

When resetting offsets, it is equally required to persist the offset information for subscription relationships that have never been online, to support scenarios where offset synchronization is needed for backup clusters.

Describe the Solution You'd Like

Assign offset in offsetTable even if the subscription key not exist for reset offset API.

Describe Alternatives You've Considered

Assign offset in offsetTable even if the subscription key not exist for reset offset API.

Additional Context

No response