[YAML] resolve variables in inlined YAML

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #11665
| License       | MIT
| Doc PR        | 

#11569 does not resolve variables in inline YAML.
That's because the asterisk has a special meaning in YAML. This wasn't handled properly before. You have to enclose it in quotes to tell the parser that it is just a main character but no reference (see also #11835 and symfony/symfony-docs#4197).