[improve] Support ClientVersion in 2.x pulsar broker

[geniusjoe]

Master Issue: #1379

Motivation

Replace pulsar go client version format Pulsar Go <version> with Pulsar-Go-<version> to support 2.x pulsar broker stats command.

Modifications

Update client version format in pulsar/internal/version.go.

Verifying this change

• Make sure that the change passes the CI checks.
  This change added tests and can be verified as follows:
  pulsar/internal/version_test.go#TestVersionHasNoSpaces

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)