fix: pin specific composer 2 versions for historic Magento releases

[rhoerr]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/mage-os/github-actions/blob/main/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Documentation content changes
• Other... Please describe:

What is the current behavior?

Fixes: Some past Magento releases in supported-versions had unpinned composer: 2 constraints, causing it to use the latest Composer 2 version for those. Those past versions are not compatible with composer 2.9.

This caused ~half of the errors in this mirror preview build: https://github.com/mage-os/generate-mirror-repo-js/actions/runs/20271742450

This fixes resulting integrity test errors by pinning them to the composer versions of the time -- 2.2 for all of the early versions in question.

What is the new behavior?

Installations will run for those versions with composer 2.2 instead of 2.9, avoiding the incompatible security audit introduced in composer 2.9.

I also set the composer version to 2.9.2 for the 'next' version (which is used only for nightlies).

Does this PR introduce a breaking change?

• Yes
• No

Other information

Tests pass:

Test Suites: 10 passed, 10 total
Tests:       69 passed, 69 total
Snapshots:   0 total
Time:        1.51 s
Ran all test suites.

[damienwebdev]

lgtm