[FrameworkBundle] Remove "doctrine/common" requirement from composer.json file.

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #9384
| License       | MIT
| Doc PR        | -

Although this maybe isn't really a feature, it brings the posibility to install a clean symfony without the need of any doctrine dependencies. Due to correct checks there shouldn't be any side effects when the doctrine requirement is removed.