[8.x] Fix require fails if is_file cached by opcache

[Tofandel]

Fixes #41613

In the case where opcache.enable_file_override is enabled, the is_file call might return true because it's cached until the end of the script so the require will fail if it was unlinked during the execution which is the case when running the command artisan config:cache
This just changes is_file to file_exists which is the method to use before a require and is not affected by this issue

[driesvints]

It's best that you explain what you're doing here or your PR will be closed (see the PR template when submitting PR's).

[driesvints]

Also if this also exists in 8.x it should be sent in to that branch: https://laravel.com/docs/9.x/contributions#which-branch

[Tofandel]

It does exist in 8.x so, I'll rebase the PR

[driesvints]

The main issue here probably is that you're enabling opcache on the CLI which I don't see a use case for.

[Tofandel]

I know but it's not always in our power to change this with some hosts because both the cli and php-fpm must have the same config file which would in turn impact performance on the front

[driesvints]

Why did you change the branch again? Can you also update the PR title when you do?

[Tofandel]

Sure, sorry

It's on 8.x, I messed up the first time

[Tofandel]

After some testing, no need for try catch, file_exists fixes the issue entirely