Improve customizability for downstream projects

The osname ("apertis" in our case) is used mainly in three places:

1. the packaging branch prefix like apertis/v2020
2. the packaging tag prefix, like apertis/1.42
3. the OBS project for the upload, like apertis:v2020:target

This MR is meant to address 2, while point 3 was addressed by commit 1d04a67d.

This MR also partially addresses point 1,with the final fix blocked by the upstream issue https://gitlab.com/gitlab-org/gitlab/-/issues/35438.

added 1 commit

• 7039d09f - ci-package-builder: Put product-specific variables at the top

Compare with previous version

@em Looks like this one needs locally rebasing.

Let's land !75 (merged) first so I can have some minimal confidence that I'm not going to break everything again. :D.

marked as a Work In Progress

changed the description

added 50 commits

• 7039d09f...ba28c15e - 48 commits from branch master
• 93465341 - ci-package-builder: More product name customizability
• 31c9b4fc - ci-package-builder: Put product-specific variables at the top

Compare with previous version

added 1 commit

• 29c022a8 - gitlab-ci: Slightly improve branch prefix customizability

Compare with previous version

added 5 commits

• 29c022a8...20ce717a - 2 commits from branch master
• e1ac61e8 - ci-package-builder: More product name customizability
• 11bf90de - ci-package-builder: Put product-specific variables at the top
• 174460fc - gitlab-ci: Slightly improve branch prefix customizability

Compare with previous version

resolved all threads

unmarked as a Work In Progress

changed title from ci-package-builder: More product name customizability to Improve customizability for downstream projects

changed the description

added 3 commits

• 7560fbe8 - ci-package-builder: Make packaging tag prefix customizable
• 4d404d53 - ci-package-builder: Put product-specific variables at the top
• 19e3fccc - gitlab-ci: Slightly improve branch prefix customizability

Compare with previous version

added 4 commits

• cf2a80ff - 1 commit from branch master
• c4aa1963 - ci-package-builder: Make packaging tag prefix customizable
• 68bc0fd0 - ci-package-builder: Put product-specific variables at the top
• 06344026 - gitlab-ci: Slightly improve branch prefix customizability

Compare with previous version

added 2 commits

• 4a4623a3 - ci-package-builder: Put product-specific variables at the top
• 8af1c36e - gitlab-ci: Slightly improve branch prefix customizability

Compare with previous version

resolved all threads

added 4 commits

• 6721c913 - 1 commit from branch master
• 22dcaea7 - ci-package-builder: Make packaging tag prefix customizable
• 0507f105 - ci-package-builder: Put product-specific variables at the top
• fabd6b2a - gitlab-ci: Slightly improve branch prefix customizability

Compare with previous version

Merging as @martyn already acknowledged it. :)

merged