This PR was merged into the 3.4 branch.

Discussion
----------

[Yaml] fix comment in multi line value

| Q             | A
| ------------- | ---
| Branch?       |  4.3 and lower <!-- see below -->
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes    <!-- please add some, will be required by reviewers -->
| Fixed tickets | #32667    <!-- #-prefixed issue number(s), if any -->
| License       | MIT
| Doc PR        | symfony/symfony-docs#... <!-- required for new features -->

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Comments after blank lines are read as value in yaml.

```
`$yaml = <<<YAML
parameters:
    abc

# Comment
YAML;

var_dump(Symfony\Component\Yaml\Yaml::parse($yaml));`
```

**Result before fix:**

```
array(1) {
  ["parameters"]=>
  string(13) "abc
# Comment"
}
```
**Result after fix:**

```
array(1) {
  ["parameters"]=>
  string(3) "abc"
}
```

Commits
-------

dd945e3 fix(yml): fix comment in milti line value