What?

Prevents duplicating nested router regions after a client-side navigation.

Nested regions may appear when an interactive block with a router region (e.g., the Query block) is placed within another interactive block with its router region (which could be another Query block instance). In this case, the nested router region is rendered twice: as part of the parent block's Preact application and as a separate Preact application, resulting in duplicated HTML.

Additionally, since a requirement of data-wp-router-region is that it must be in the top-most data-wp-interactive element, this PR ensures that it ignores all regions that do not meet this requirement.

Why?

Nested router regions should not be processed; only the top-most region should, as nested regions become part of the same Preact application.

How?

Changing the selector to only take into account the regions that are not nested and that also include a top-most data-wp-interactive element.

The PR includes e2e tests for this bug fix.