feat(tier4_state_rviz_plugin): change to read topic by polling

[Autumn60]

Description

Based on the discussion, change tier4_state_rviz_plugin to read topic by polling instead of best_effort callback.

During this change, VelocitySteeringFactorsPanel became timer-driven.

Tests performed

Not applicable.

Effects on system behavior

Not applicable.

Interface changes

Pre-review checklist for the PR author

The PR author must check the checkboxes below when creating the PR.

• I've confirmed the contribution guidelines.
• The PR follows the pull request guidelines.

In-review checklist for the PR reviewers

The PR reviewers must check the checkboxes below before approval.

• The PR follows the pull request guidelines.

Post-review checklist for the PR author

The PR author must check the checkboxes below before merging.

• There are no open discussions or they are tracked via tickets.

After all checkboxes are checked, anyone who has write access can merge the PR.

[isamu-takagi]

I don't think this change will make much difference in performance. Since takeNewData takes messages from the queue in order, the same number of messages are processed, and there is more wasted processing because of polling.

[Autumn60]

@isamu-takagi
Thanks for your opinion.
As you say, if the frequency at which messages are sent is lower than the loop rate (20 Hz), then all messages will be processed.

So I consider this change as a "performance stabilization" rather than a "performance improvement".
As for "CPU load independent of external topic frequency", this PR makes sense.

[isamu-takagi]

Thank you. The PR purpose makes sense. However, since the main purpose of this debug tool is to check data, it is more important to process all data than performance, so I would like to continue using the callback method.

[Autumn60]

@isamu-takagi

Thank you very much for your detailed explanation. 🙏
I will close the PR here and leave the callback as is.