Seek fails on non-partitioned topics due to partition check in Go client

### Expected behavior

The `Seek` method should not check for partition-specific logic when working with non-partitioned topics. It should simply seek to the specified message ID without involving partition indices.

### Actual behavior

The `Seek` method fails with an error related to partition indices when called on a non-partitioned topic. The error message suggests that the `Seek` command should be performed on individual partitions, even though the topic is not partitioned.

Error: `invalid partition index -1 expected a partition between [0-1]"`

### Steps to reproduce

1. Create a non-partitioned topic.
2. Use the `Seek` method with `pulsar.EarliestMessageID()` on this topic.
3. Observe that an error is returned due to partition-specific logic being applied, even though the topic is non-partitioned.

### System configuration

**Pulsar version**: 3.3.2
**Pulsar Go client version**: v0.13.1

Start by locating the Go client's Seek method and trace how it handles non-partitioned topics and partition indices. Reproduce the issue with a non-partitioned topic and pulsar.EarliestMessageID(), then verify that seeking succeeds without the invalid partition index error.

Written by the indexing model from the issue text.