Use class method 'sort' to get last_version_for_major

What does this MR do and why?

Describe in detail what your merge request does and why.

Content

Fix ReleaseTools::Versions.last_version_for_major

• Revert !4124 (merged)
• Sort returned versions from version.gitlab.com by Gem::Version to make sure the latest version is always on top
• Actualize the VCR file versions/list.yml to include the actual situation when the first version in the list is not the latest one

Ref: gitlab-com/gl-infra/delivery#21073 (closed)

Test

Before

The wrong last version is returned

[1] pry(main)> ReleaseTools::Versions.last_version_for_major(17)
=> "17.9.7"

After

The right last version is returned

[5] pry(main)> ReleaseTools::Versions.last_version_for_major(17)
=> "17.11.1"
[6] pry(main)> ReleaseTools::Versions.last_version_for_major(18)
=> nil