[FrameworkBundle] cache:clear command fills *.php.meta files with wrong data

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | no
| Fixed tickets | #12110
| License       | MIT

This PR added only failing unit test, which shows what was described in #12110
TestAppKernel would sound better. Some IDE's (such as eclipse) will index this file and provide auto complete on it or quick searches. That means that besides of the AppKernel in your own applications, you will always see a second pop up. This can be confusing.