deploy: Fix deploy defaults for non-zero flag values (e.g. maxDeletes, invalidateCDN)

This was broken in the config rewrite in Hugo 0.112.0.

The workaround is to be explicit about setting these flag values (even if just using the defaults), e.g.:

```
hugo deploy --invalidateCDN --maxDeletes 256
```

Fixes #11127

testscripts/commands/deploy.txt

@@ -3,10 +3,10 @@
 hugo deploy -h
 stdout 'Deploy your site to a Cloud provider\.'
 mkdir mybucket
-hugo deploy --target mydeployment
+hugo deploy --target mydeployment --invalidateCDN=false
 grep 'hello' mybucket/index.html
 replace  public/index.html 'hello' 'changed'
-hugo deploy --target mydeployment --invalidateCDN --dryRun
+hugo deploy --target mydeployment --dryRun
 stdout 'Would upload: index.html'
 stdout 'Would invalidate CloudFront CDN with ID foobar'
 -- hugo.toml --