PLACEHOLDER still problematic on main (at least) for branch dev/reopen

a fix was added in toolshed to add a placeholder when reopening branches

this added or ommitted .txt and didnt work - i thought i had rolled out a fix - but perhaps only oin release branches

the better fix is to remvoe the legacy changelog code and the need for the placeholder at all

Start by tracing the toolshed logic used when reopening branches, especially the legacy changelog handling and placeholder creation for dev/reopen on main. Remove the legacy changelog code and placeholder requirement, then verify that reopening the branch no longer adds or omits a .txt placeholder.

Written by the indexing model from the issue text.