Use curl instead of AWS CLI (#2689)

The latter starts up significantly slower which impedes integration
test times.  curl has some limitations, e.g., no SSE support.

.github/workflows/ci.yml

@@ -140,11 +140,6 @@ jobs:
             if brew list | grep -q ${s3fs_brew_pkg}; then if brew outdated | grep -q ${s3fs_brew_pkg}; then HOMEBREW_NO_AUTO_UPDATE=1 brew upgrade ${s3fs_brew_pkg}; fi; else HOMEBREW_NO_AUTO_UPDATE=1 brew install ${s3fs_brew_pkg}; fi
           done
 
-      - name: Install awscli2
-        run: |
-          curl "https://awscli.amazonaws.com/AWSCLIV2.pkg" -o /tmp/AWSCLIV2.pkg
-          sudo installer -pkg /tmp/AWSCLIV2.pkg -target /
-
       - name: Build
         run: |
           ./autogen.sh