BF: publish: Tell git-fetch to not recurse into submodules

[kyleam]

publish() fetches the sibling before pushing, and has done so for a
long time (f07fc51, 2017-08-26). If the fetch brings down a
recorded submodule commit that is not yet present locally, by default
git also fetch in the submodule with the missing commit.

This is problematic because, as explained in dbd84e5 (ENH: update:
Try to fetch submodule commit explicitly if needed, 2020-02-07),
submodule.c hard codes 'origin' as a fallback to fetch from, so the
fetch will fail unless there's a remote named 'origin'. Also,
conceptually, the goal of this fetch seems to be to obtain up-to-date
information on the current repository, not its submodules, which
publish() will handle itself if called with --recursive.

Fetch with --recurse-submodules=no.

[kyleam]

Note: I've checked push. It doesn't seem to have this issue.

[codecov]

Codecov Report

Merging #4560 into maint will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##            maint    #4560   +/-   ##
=======================================
  Coverage   90.10%   90.11%           
=======================================
  Files         275      275           
  Lines       37118    37133   +15     
=======================================
+ Hits        33447    33462   +15     
  Misses       3671     3671           

Impacted Files	Coverage Δ
datalad/distribution/publish.py	87.93% <100.00%> (ø)
datalad/distribution/tests/test_publish.py	100.00% <100.00%> (ø)

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[yarikoptic]

Thanks!