fix(worker): Ignore git-annex remotes marked dead

[nellh]

This is a better fix for #3145 - instead of picking a remote by name, test for dead remotes. In the future we might want to consider the other trust levels but this makes it possible to push a git-annex repo where a remote was marked dead at some point without dropping history and get a correct result regardless of remote names.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 19 lines in your changes missing coverage. Please review.

Project coverage is 44.02%. Comparing base (b4e6f3d) to head (a4cab7f).
Report is 2 commits behind head on master.

Files with missing lines	Patch %	Lines
services/datalad/datalad_service/common/annex.py	0.00%	19 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3147      +/-   ##
==========================================
- Coverage   44.04%   44.02%   -0.02%     
==========================================
  Files         593      593              
  Lines       37790    37803      +13     
  Branches     1124     1124              
==========================================
+ Hits        16643    16644       +1     
- Misses      20945    20957      +12     
  Partials      202      202              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.