[improve] Update deliverAfter and deliverAt api comment

[geniusjoe]

Contribution Checklist

Master Issue: apache/pulsar#23968

Motivation

Related Issue: apache/pulsar-site#507

We now support consuming delayed messages with shared and Key-shared type subscriptions, which has been corrected since pulsar 3.x doc in above pr.

But Golang code deliverAt and deliverAfter comment says we can only support Shared type subscription, so that maybe we need to fix them.

Modifications

Replace SubscriptionType=Shared comment with SubscriptionType=Shared or SubscriptionType=KeyShared in deliverAt and deliverAfter api.

Verifying this change

• Make sure that the change passes the CI checks.
  This change is a trivial rework / code cleanup without any test coverage.

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): (no)
• The public API: (no)
• The schema: (no)
• The default values of configurations: (no)
• The wire protocol: (no)

Documentation

• Does this pull request introduce a new feature? (no)
• If yes, how is the feature documented? (not documented)