Migrate to aws sdk v2

[smallhive]

Tested with the latest versions:

boto3                     1.37.24
botocore                  1.37.24

aws-cli/2.25.3

[codecov]

Codecov Report

Attention: Patch coverage is 1.44928% with 272 lines in your changes missing coverage. Please review.

Project coverage is 25.77%. Comparing base (fcb4791) to head (e720f27).
Report is 13 commits behind head on master.

Files with missing lines	Patch %	Lines
api/auth/signer/v4/chunked_reader.go	0.00%	157 Missing ⚠️
api/auth/center.go	3.22%	60 Missing ⚠️
api/auth/signer/v4/checksum_algorithm.go	0.00%	45 Missing ⚠️
api/handler/multipart_upload.go	33.33%	3 Missing and 1 partial ⚠️
api/auth/signer/v4/chunk_signer.go	0.00%	2 Missing ⚠️
api/auth/signer/v4/stream.go	0.00%	2 Missing ⚠️
api/layer/detector.go	0.00%	0 Missing and 1 partial ⚠️
api/layer/multipart_upload.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1113      +/-   ##
==========================================
- Coverage   26.00%   25.77%   -0.24%     
==========================================
  Files          88       89       +1     
  Lines       15420    15572     +152     
==========================================
+ Hits         4010     4013       +3     
- Misses      10953    11103     +150     
+ Partials      457      456       -1     

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