Discontinue usage of deprecated (public) helper

[mih]

Fixes #6030

This is an alternative to #6031 which maintains the general direction, while avoiding the complications.

[codecov]

Codecov Report

Merging #6032 (1896a34) into maint (53183e3) will decrease coverage by 1.70%.
The diff coverage is 100.00%.

❗ Current head 1896a34 differs from pull request most recent head 066e3af. Consider uploading reports for the commit 066e3af to get more accurate results

@@            Coverage Diff             @@
##            maint    #6032      +/-   ##
==========================================
- Coverage   90.19%   88.48%   -1.71%     
==========================================
  Files         315      312       -3     
  Lines       42165    42152      -13     
==========================================
- Hits        38030    37300     -730     
- Misses       4135     4852     +717     

Impacted Files	Coverage Δ
datalad/cmd.py	85.27% <100.00%> (-5.28%)	⬇️
datalad/tests/test_installed.py	90.00% <100.00%> (+1.11%)	⬆️
datalad/plugin/wtf.py	0.00% <0.00%> (-100.00%)	⬇️
datalad/plugin/addurls.py	0.00% <0.00%> (-100.00%)	⬇️
datalad/plugin/no_annex.py	0.00% <0.00%> (-100.00%)	⬇️
datalad/plugin/add_readme.py	0.00% <0.00%> (-100.00%)	⬇️
datalad/plugin/check_dates.py	0.00% <0.00%> (-100.00%)	⬇️
datalad/support/tests/utils.py	0.00% <0.00%> (-100.00%)	⬇️
datalad/plugin/export_archive.py	0.00% <0.00%> (-100.00%)	⬇️
datalad/plugin/export_to_figshare.py	0.00% <0.00%> (-100.00%)	⬇️
... and 69 more

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