Recover "awsregion" parameter for registry-creds addon

[dragon3]

It seems the "awsregion" parameter was removed in 8ba6f47 (#1711) unexpectedly.
It caused making incorrect awsecr-cred with unexpected aws region.

see also: #1757 (comment)

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[dragon3]

I've just signed the CLA.

[codecov-io]

Codecov Report

Merging #1888 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1888   +/-   ##
=======================================
  Coverage   32.23%   32.23%           
=======================================
  Files          69       69           
  Lines        4104     4104           
=======================================
  Hits         1323     1323           
  Misses       2608     2608           
  Partials      173      173

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[r2d4]

I'm not too familar with this part of the code, but it looks like we want to just add back in aws-region, while keeping aws-account

[dragon3]

@r2d4 Yes, correct.
Before this pull request, there were duplicated aws-account definitions, and if there is no aws-region parameter, registry-creds addon doesn't work properly.

[r2d4]

Got it, thanks!