[Enhancement] Improve Lite subscription quota validation for remove actions

Start at ClientProcessor#syncLiteSubscription and trace how liteTopicSet, liteSubClientQuota, quotaBuffer, and the four subscription actions are handled. Done means quota validation remains for PARTIAL_ADD and COMPLETE_ADD, is skipped for PARTIAL_REMOVE and COMPLETE_REMOVE, and the relevant behavior is covered by the repository's existing tests.

Before Creating the Enhancement Request

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

Summary

Improve Lite subscription quota validation in proxy by applying the quota check only to Lite subscription add actions.

Currently, proxy validates liteTopicSet.size() against liteSubClientQuota + quotaBuffer before syncing Lite subscriptions. This validation should apply to PARTIAL_ADD and COMPLETE_ADD, but not to remove actions.

Motivation

Lite subscription quota is used to limit subscription growth. Remove actions release existing subscriptions and should not be blocked by the same quota validation.

For example, a client may add Lite subscriptions in several smaller PARTIAL_ADD requests and later remove them in one larger PARTIAL_REMOVE request. The remove request can contain more Lite topics than the quota threshold, but it only reduces the active subscription set.

Describe the Solution You'd Like

Update ClientProcessor#syncLiteSubscription so that Lite subscription quota validation is only applied to add actions:

• PARTIAL_ADD
• COMPLETE_ADD

Skip this quota validation for remove actions:

• PARTIAL_REMOVE
• COMPLETE_REMOVE

This keeps the quota protection for subscription growth while allowing large unsubscribe requests to release resources normally.

Describe Alternatives You've Considered

One alternative is to keep validating all actions with non-empty liteTopicSet, but this treats remove requests as if they were adding subscriptions.

Another alternative is to introduce a separate request-size limit for Lite subscription sync requests. That may be useful independently, but it should not reuse LITE_SUBSCRIPTION_QUOTA_EXCEEDED, because subscription quota and request size are different concepts.

Additional Context

No response