[Issue] [vcl] Better debug

[m2-assistant[bot]]

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This issue is automatically created based on existing pull request: magento/magento2#28944: [vcl] Better debug

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Detecting if the response is a hit usingthe x-varnish header is flaky and notably doesn't work in a multi-tier setup.

On top of this, HIT/MISS is a false dichotomy (https://info.varnish-software.com/blog/using-obj-hits) and while I'd like something more detailed like https://docs.varnish-software.com/tutorials/hit-miss-logging/ (tech version of the blog), I recognize that it's "a lot" of VCL, so this commit only differentiates between hits, misses and passes, the latter being pretty useful to identify while debugging.

note: all versions have been changed for the sake of consistency but both the 4.x and 5.x series have been EOL'd a (long) while ago and users should be encouraged to upgraded as soon as possible.

Contribution checklist (*)

• [ ] Pull request has a meaningful description of its purpose
• [ ] All commits are accompanied by meaningful commit messages
• [ ] All new or changed code is covered with unit/integration tests (if applicable)
• [ ] All automated tests passed successfully (all builds are green)