Make .gitignore excluded by default from new mirror versions

[Vinai]

Currently the Magento Open Source releases that don't include a .gitignore file in the project root are listed in an array in src/build-config/packages-config.js:

const releasesWithoutGitIgnore = ['2.4.1', '2.4.1-p1', '2.4.2', '2.4.4-p3', '2.4.4-p4', '2.4.4-p5', '2.4.4-p6', '2.4.5-p2', '2.4.5-p3', '2.4.5-p4', '2.4.5-p5', '2.4.6', '2.4.6-p1', '2.4.6-p2', '2.4.6-p3'];

However, new upstream releases all seem to exclude the .gitignore, so the array needs to be updated with the new versions for each new release.

This is error prone and has slowed down adding new releases to the mage-os mirror repo several times in the past.
The default should be changed to a list of releases that include a .gitignore instead.