[Performance][Testing] Avoid double call FileSystem::read() on AbstractRectorTestCase

[samsonasik]

When calling:

$this->applicationFileProcessor->processFiles([$filePath], $configuration);

The CurrentFileProvider service is set to File object with its originalContent and new content, so we no longer need to re-read file.

This PR make pull from CurrentFileProvider service.

[samsonasik]

Github action error seems unrelated:

Download action repository 'actions/checkout@v3' (SHA:f43a0e5ff2bd294095638e18286ca9a3d1956744)
Error: Can't use 'tar -xzf' extract archive file: /home/runner/work/_actions/_temp_4ecd32f5-c361-435e-b74b-7171ccb18414/3c125ce6-395a-4023-acd8-39fc47eba947.tar.gz. return code: 2.

[samsonasik]

It seems bug on github checkout:

• Can't use 'tar -xzf' extract archive file actions/checkout#1448

I will try update to github checkout v4 on separate PR.

[samsonasik]

Github actions/checkout updated to v4 on PR:

• Update github actions/checkout from v3 to v4 #4909

and this now rebased.

[samsonasik]

All checks have passed 🎉 @TomasVotruba I think it is ready.

[samsonasik]

@TomasVotruba I am merging it ;)