Fixes for backup remote exports and annex drop

[nellh]

• Block less often with async coroutines for S3 export tasks
• Fix an issue with credentials that would cause drop to fail depending on how the s3 remote was configured
• Fix a bug with an extra argument for the fsck / drop pipeline

[codecov]

Codecov Report

❌ Patch coverage is 50.00000% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 42.99%. Comparing base (403fb1e) to head (66ba43c).
⚠️ Report is 6 commits behind head on master.

Files with missing lines	Patch %	Lines
services/datalad/datalad_service/tasks/publish.py	28.57%	5 Missing ⚠️
services/datalad/datalad_service/common/s3.py	57.14%	3 Missing ⚠️
services/datalad/datalad_service/common/asyncio.py	75.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #3639   +/-   ##
=======================================
  Coverage   42.98%   42.99%           
=======================================
  Files         635      635           
  Lines       33809    33817    +8     
  Branches     1518     1518           
=======================================
+ Hits        14534    14538    +4     
- Misses      19136    19140    +4     
  Partials      139      139           

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[effigies]

The default value of env is already None: https://docs.python.org/3/library/subprocess.html#subprocess.Popen

Suggested change

	if env:
	process = await asyncio.create_subprocess_exec(
	*command,
	cwd=dataset_path,
	env=env,
	stdout=asyncio.subprocess.PIPE,
	stderr=asyncio.subprocess.PIPE,
	)
	else:
	process = await asyncio.create_subprocess_exec(
	*command,
	cwd=dataset_path,
	stdout=asyncio.subprocess.PIPE,
	stderr=asyncio.subprocess.PIPE,
	)
	process = await asyncio.create_subprocess_exec(
	*command,
	cwd=dataset_path,
	env=env,
	stdout=asyncio.subprocess.PIPE,
	stderr=asyncio.subprocess.PIPE,
	)

Did you find this made a difference in practice?