[#5358] split up markdown tests, clean up & speed up test contexts

@with_setup(setUp) is duplicative since setUp already runs.  Clean up the set_context
and wiki dependencies that that was masking.
[#5358] allow markdown escapes within autolinked URLs
[#5810] add colon before instance-specific log data, for easier log parsing later
[#5810] standardize slashes in tree_paths