Whether FPS transition should clear a site's data partitioned by other top-levels.

[shuranhuang]

E.g. if site A has a FPS membership change, currently the FPS transition clearing would clear:

1. A's unpartitioned data; and
2. all third-party resources partitioned under A being top-level;

which is similar to the case when CRD is sent in the first-party context proposed here.

But should the clearing also cover 3. A's resources partitioned under other top-levels? See https://github.com/privacycg/storage-partitioning/issues/11 for an explanation of why this might be undesirable.