[FrameworkBundle] Removed unused code from cache clear command

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

This is how a `$search` `$replace` variables look like:

```php
array(2) {
  [0] =>
  string(43) "/home/egabor/dev/site/app/cache/de_"
  [1] =>
  string(43) "/home/egabor/dev/site/app/cache/de_"
}
string(43) "/home/egabor/dev/site/app/cache/dev"
```
After the paths in the generated container were changed to be relative these paths will not appear in the file so I think it can be removed safely.