fix: turn on FNN in struct used during site creation (#2655)

REST DB migrations were created to default new sites to FNN VPC
creation, but a struct being used during site creation is overriding
that.

This PR default fixes that to so new default to FNN.

## Related issues
<!-- Refer to existing GitHub issues here -->

#2522

<!-- Describe what this PR does -->
## Type of Change
<!-- Check one that best describes this PR -->
- [ ] **Add** - New feature or capability
- [ ] **Change** - Changes in existing functionality
- [ ] **Fix** - Bug fixes
- [ ] **Remove** - Removed features or deprecated functionality
- [ ] **Internal** - Internal changes (refactoring, tests, docs, etc.)

## Breaking Changes
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<!-- Breaking changes are not generally permitted, please discuss on a
GitHub discussion or with the development team if you believe you need
to break a backward compatibility guarantee -->
- [ ] **This PR contains breaking changes**

## Testing
<!-- How was this tested? Check all that apply -->
- [ ] Unit tests added/updated
- [x] Integration tests added/updated
- [ ] Manual testing performed
- [ ] No testing required (docs, internal refactor, etc.)

## Additional Notes
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Author: bcavnvidia

rest-api/api/pkg/api/handler/site.go

@@ -168,8 +168,10 @@ func (csh CreateSiteHandler) Handle(c echo.Context) error {
 			IsSerialConsoleEnabled:   false,
 			Status:                   cdbm.SiteStatusPending,
 			CreatedBy:                dbUser.ID,
+			// New sites default to the v2 networking posture.
 			Config: cdbm.SiteConfig{
-				NetworkSecurityGroup: true, // The default case for a new site is to support NSGs.
+				NativeNetworking:     true,
+				NetworkSecurityGroup: true,
 			},
 		}
 		if apiRequest.Location != nil {

rest-api/api/pkg/api/handler/site_test.go

@@ -504,6 +504,19 @@ func TestCreateSiteHandler_Handle(t *testing.T) {
 
 				assert.Equal(t, rst.Status, cdbm.SiteStatusPending)
 				assert.Equal(t, len(rst.StatusHistory), 1)
+				require.NotNil(t, rst.Capabilities)
+				assert.True(t, rst.Capabilities.NativeNetworking)
+				assert.True(t, rst.Capabilities.NetworkSecurityGroup)
+
+				createdSiteID, perr := uuid.Parse(rst.ID)
+				require.NoError(t, perr)
+				createdSite, gerr := cdbm.NewSiteDAO(tt.fields.dbSession).GetByID(
+					context.Background(), nil, createdSiteID, nil, false,
+				)
+				require.NoError(t, gerr)
+				require.NotNil(t, createdSite.Config)
+				assert.True(t, createdSite.Config.NativeNetworking)
+				assert.True(t, createdSite.Config.NetworkSecurityGroup)
 
 				if !tt.siteMgrDisabled {
 					assert.NotNil(t, rst.RegistrationToken)