Rename properties and binder name for eventhubs binder

[saragluna]

Description

Rename event hubs binder name and properties prefix from eventhub to eventhubs, and refactor some classes names accordingly. Also, this pr remove the duplicate EventHubProvisioner.

All SDK Contribution checklist:

• The pull request does not introduce [breaking changes]
• CHANGELOG is updated for new features, bug fixes or other significant changes.
• I have read the contribution guidelines.

General Guidelines and Best Practices

• Title of the pull request is clear and informative.
• There are a small number of commits, each of which have an informative message. This means that previously merged commits do not appear in the history of the PR. For more information on cleaning up the commits in your PR, see this page.

Testing Guidelines

• Pull request includes test coverage for the included changes.

[saragluna]

/azp run java - spring - tests

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[yiliuTo]

LGTM