[fix][java-client] Skip TopicListWatcher creation when lookup url scheme is HTTP

[andrasbeni]

TopicListWatchers need a ClientCnx to communicate to a broker, but they have no topic to discover the owner. So they rely on the lookup URL. When the scheme is HTTP, no ClientCnx can be created with it.

Modifications

• Not creating a TopicListWatcher when HTTP URL is specified
• Added a test to avoid future regressions in this area

Verifying this change

• Make sure that the change passes the CI checks.

This change added a test

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

If yes was chosen, please highlight the changes

• 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)
• The rest endpoints: (no)
• The admin cli options: (no)
• Anything that affects deployment: (no)

Documentation

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Need to update docs?

• doc-not-needed
  This is a bug fix. The whole feature needs to be documented as stated on [feat][broker] PIP-145: Notifications for faster topic discovery #16062