mergestate: remove unrequired RECORD_RESOLVED_OTHER record
This was introduced in last cycle however while working on refactoring
mergestate, I realized it's unncessary.
This will break users who did a merge using previous version, did this kind of
storage and before commiting updated the mercurial version.
Differential Revision: https://phab.mercurial-scm.org/D8716
mergestate: rename addpath() -> addpathonflict() to prevent confusion
addpath() seems to imply that we are adding a new path/entry to the mergestate.
Differential Revision: https://phab.mercurial-scm.org/D8715