HOSTEDCP-2231: Remove cloud connection, Set Transit Gateway as default

[aman4433]

What this PR does / why we need it: This PR updates the PowerVS documentation and code to reflect Transit Gateway as the default networking mode. IBM Cloud has removed support for cloud connection, necessitating this change.

• Removed references to cloud connection.
• Updated hypershift powervs commands to use Transit Gateway as the default networking mode.
• Revised the documentation to provide clear guidance on Transit Gateway usage.

Which issue(s) this PR fixes (optional, use fixes #<issue_number>(, fixes #<issue_number>, ...) format, where issue_number might be a GitHub issue, or a Jira story: Fixes #5062

Checklist

• Subject and description added to both, commit and PR.
• Relevant issues have been referenced.
• This change includes docs.
• This PR was tested locally.

[openshift-ci-robot]

@aman4433: This pull request references HOSTEDCP-2231 which is a valid jira issue.

Warning: The referenced jira issue has an invalid target version for the target branch this PR targets: expected the story to target the "4.19.0" version, but no target version was set.

In response to this:

What this PR does / why we need it: This PR updates the PowerVS documentation and code to reflect Transit Gateway as the default networking mode. IBM Cloud has removed support for cloud connection, necessitating this change.

• Removed references to cloud connection.
• Updated hypershift powervs commands to use Transit Gateway as the default networking mode.
• Revised the documentation to provide clear guidance on Transit Gateway usage.

Which issue(s) this PR fixes (optional, use fixes #<issue_number>(, fixes #<issue_number>, ...) format, where issue_number might be a GitHub issue, or a Jira story: Fixes #5062

Checklist

• Subject and description added to both, commit and PR.
• Relevant issues have been referenced.
• This change includes docs.
• This PR was tested locally.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the openshift-eng/jira-lifecycle-plugin repository.

[openshift-ci]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: aman4433
Once this PR has been reviewed and has the lgtm label, please assign jparrill for approval. For more information see the Code Review Process.

The full list of commands accepted by this bot can be found here.

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[openshift-ci]

Hi @aman4433. Thanks for your PR.

I'm waiting for a openshift member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

I understand the commands that are listed here.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.