Fix for diff-root, and ignore most FTAG changes in ESDs

The utility acmd diff-root would report changes if new branches were added or branches were deleted, even if these branches were in the --ignore-leaves list. This fixes that behavior.

I'm also excluding most of b-tagging from the frozen tier0 ESD check, as agreed in the weekly reconstruction meeting. This is required for @alfroch's additions in !53961 (merged).