refactor: replace AWS SDK with a REST client for CodeCommit migration (#39330)

Replace `aws-sdk-go-v2` in the CodeCommit migration with a minimal REST
client for the four read-only API calls it uses. Binary shrinks by ~3.1
MB.

Mock data was recorded against live from a AWS CodeCommit repo and then
anonymized.

Also stop storing the repo description as the default branch which fixes
below issue. All comments in
https://github.com/go-gitea/gitea/issues/34627 are addressed, the merge
metadata was fixed earlier in
https://github.com/go-gitea/gitea/pull/34645.

Fixes: https://github.com/go-gitea/gitea/issues/34627

go.mod

@@ -22,8 +22,6 @@ require (
 	github.com/PuerkitoBio/goquery v1.13.0
 	github.com/SaveTheRbtz/zstd-seekable-format-go/pkg v0.10.0
 	github.com/alecthomas/chroma/v2 v2.27.0
-	github.com/aws/aws-sdk-go-v2/credentials v1.20.3
-	github.com/aws/aws-sdk-go-v2/service/codecommit v1.42.0
 	github.com/blakesmith/ar v0.0.0-20190502131153-809d4375e1fb
 	github.com/blevesearch/bleve/v2 v2.6.1
 	github.com/bohde/codel v0.2.0
@@ -126,10 +124,6 @@ require (
 	github.com/STARRY-S/zip v0.2.3 // indirect
 	github.com/andybalholm/brotli v1.2.1 // indirect
 	github.com/andybalholm/cascadia v1.3.4 // indirect
-	github.com/aws/aws-sdk-go-v2 v1.46.0 // indirect
-	github.com/aws/aws-sdk-go-v2/internal/configsources v1.5.2 // indirect
-	github.com/aws/aws-sdk-go-v2/internal/endpoints/v2 v2.8.2 // indirect
-	github.com/aws/smithy-go v1.28.1 // indirect
 	github.com/aymerick/douceur v0.2.0 // indirect
 	github.com/beorn7/perks v1.0.1 // indirect
 	github.com/bits-and-blooms/bitset v1.24.5 // indirect