minor #25652 Clean up (carusogabriel)

This PR was squashed before being merged into the 2.7 branch (closes #25652).

Discussion
----------

Clean up

| Q             | A
| ------------- | ---
| Branch?       | 2.7
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

I've removed all white spaces and extra lines from our `markdown` files. Recently [I did it in our documentation](https://github.com/symfony/symfony-docs/pull/8944), and thought would be interesting to replicate here 😄

Commits
-------

acd0d7c Clean up

UPGRADE-2.2.md

@@ -26,7 +26,6 @@
  * The `standalone` option is deprecated and will be replaced with the `strategy` option in 2.3.
  * The values `true`, `false`, `js` for the `standalone` option were deprecated and replaced respectively with the `esi`, `inline`, `hinclude` in 2.3.
 
-
    Before:
 
    ```jinja
@@ -43,7 +42,6 @@
    {{ render(controller('BlogBundle:Post:list', { 'limit': 2 }), { 'strategy': 'hinclude'}) }}
    ```
 
-
 ### HttpFoundation
 
  * The MongoDbSessionHandler default field names and timestamp type have changed.

UPGRADE-2.5.md

@@ -245,7 +245,6 @@ Validator
        ->getValidator();
    ```
 
-
 Yaml Component
 --------------
 

UPGRADE-3.0.md

@@ -49,7 +49,6 @@ UPGRADE FROM 2.x to 3.0
    `DebugClassLoader`. The difference is that the constructor now takes a
    loader to wrap.
 
-
 ### Config
 
  * The `__toString()` method of the `\Symfony\Component\Config\ConfigCache` class