fix: restore push-to-nuget default to true after OIDC configuration

OIDC trust policy has been configured on NuGet.org. Also remove
unnecessary .NET 8.0 SDK installation (only .NET 10 is needed).

Co-Authored-By: Claude <noreply@anthropic.com>

Author: JusterZhu

.github/workflows/publish-nuget.yml

@@ -11,7 +11,7 @@ on:
         description: 'Push package to NuGet.org (requires OIDC trust policy configured)'
         required: false
         type: boolean
-        default: false
+        default: true
 
 permissions:
   contents: write
@@ -40,7 +40,6 @@ jobs:
         uses: actions/setup-dotnet@v4
         with:
           dotnet-version: |
-            8.0.x
             10.0.x
 
       - name: Install Android workload