Makefile adjustments & simplification

[eskultety]

• move the pip-compile to a docker image to drop the need to have python 3.9 always installed on the dev machine just to be able to run pip-compile correctly
• simplify the Makefile somewhat as a direct result of the ^above
• drop the generate-test-data target

Maintainers will complete the following section

• [x] Commit messages are descriptive enough
• [n/a] Code coverage from testing does not decrease and new code is covered
• [n/a] Docs updated (if applicable)
• [n/a] Docs links in the code are still valid (if docs were updated)

[eskultety]

Worth noting that I tested the changes in clean Ubuntu 24.04 and Fedora 40 VMs just to make sure that e.g. Ubuntu doesn't choke on the 'Z' volume permission and that nothing I have locally installed didn't affect the patches.

[eskultety]

Reworded the commit messages slightly to remove some obvious typos and stylistic issues.

[MartinBasti]

@eskultety FYI, I don't have approval permissions

[eskultety]

@eskultety FYI, I don't have approval permissions

not this again