chore: update setup-go action to fix Go download failures (#22306)

setup-go has been sporadically failing to download Go, and we were advised
by a member of the Go team that downloading Go from `storage.googleapis.com`
is not guaranteed (which is what setup-go <= v5.6.0 does).

Also remove the use-preinstalled-go optimization for Windows runners.
setup-go v6 sets GOTOOLCHAIN=local, which prevents the pre-installed
Go from auto-downloading the toolchain specified in go.mod. The windows
optimization with v5 relied on GOTOOLCHAIN=auto. setup-go uses the runner
cache, which is a different caching path but should serve the same purpose.

.github/workflows/ci.yaml

@@ -422,10 +422,6 @@ jobs:
       - name: Setup Go
         uses: ./.github/actions/setup-go
         with:
-          # Runners have Go baked-in and Go will automatically
-          # download the toolchain configured in go.mod, so we don't
-          # need to reinstall it. It's faster on Windows runners.
-          use-preinstalled-go: ${{ runner.os == 'Windows' }}
           use-cache: true
 
       - name: Setup Terraform

.github/workflows/nightly-gauntlet.yaml

@@ -64,11 +64,6 @@ jobs:
 
       - name: Setup Go
         uses: ./.github/actions/setup-go
-        with:
-          # Runners have Go baked-in and Go will automatically
-          # download the toolchain configured in go.mod, so we don't
-          # need to reinstall it. It's faster on Windows runners.
-          use-preinstalled-go: ${{ runner.os == 'Windows' }}
 
       - name: Setup Terraform
         uses: ./.github/actions/setup-tf