fix(nebula node container): fix if condition for ring outlier filter

[vividf]

Description

The previous parameter output_frame in ring outlier filter will always change from base_link back to sensor_frame because the if LaunchConfiguration("output_as_sensor_frame").perform(context) is always true.

That is because LaunchConfiguration("output_as_sensor_frame").perform(context) is a string.

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.

[YoshiRi]

Thanks! LGTM