fix: Use unique data-sort attributes

[larseggert]

So list.js properly sorts columns.

[codecov]

Codecov Report

Merging #3836 (db691d9) into main (ef4ad54) will increase coverage by 0.03%.
The diff coverage is 98.73%.

@@            Coverage Diff             @@
##             main    #3836      +/-   ##
==========================================
+ Coverage   87.95%   87.99%   +0.03%     
==========================================
  Files         296      297       +1     
  Lines       38795    38769      -26     
==========================================
- Hits        34124    34116       -8     
+ Misses       4671     4653      -18     

Impacted Files	Coverage Δ
ietf/meeting/models.py	86.08% <ø> (ø)
ietf/meeting/urls.py	100.00% <ø> (ø)
ietf/meeting/utils.py	90.27% <ø> (-0.29%)	⬇️
ietf/name/models.py	100.00% <ø> (ø)
ietf/meeting/views.py	91.02% <96.00%> (+0.42%)	⬆️
ietf/doc/templatetags/ballot_icon.py	84.89% <100.00%> (ø)
ietf/doc/templatetags/ietf_filters.py	81.40% <100.00%> (+0.15%)	⬆️
ietf/doc/views_ballot.py	91.60% <100.00%> (ø)
ietf/doc/views_charter.py	88.72% <100.00%> (ø)
ietf/doc/views_status_change.py	93.04% <100.00%> (ø)
... and 14 more

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