scripts/get-version-from-git returns v2.9.8-* if not run from master branch

[hdiethelm]

scripts/get-version-from-git returns v2.9.8-* if on any other branch than master. This can also be tested locally and gives the version number for ci packages.

Visible for example here:
https://github.com/LinuxCNC/linuxcnc/actions/runs/25918823003/job/76182201627#step:7:41

If you download aftefacts from here (branch based on master) the packages are named 2.9.8:
https://github.com/LinuxCNC/linuxcnc/actions/runs/25918823003

If you download artefacts built on master, the packages are named 2.10.0~pre.0:
https://github.com/LinuxCNC/linuxcnc/actions/runs/25905258421

Note, this has nothing to do with my ci improvements, same issue here:
https://github.com/LinuxCNC/linuxcnc/actions/runs/25624363327/job/75216663466#step:7:47

[hdiethelm]

The issue is in here:
https://github.com/LinuxCNC/linuxcnc/blob/master/scripts/githelper.sh

If not on master branch, it selects the newest tag. Due to the tag v2.10.0-pre0 is older than v2.9.8, the version for all branches except master shows v2.9.8 which is probably not desired.

An easy solution would be to drop this script and only use the VERSION file. This would mean remove the following lines:
https://github.com/LinuxCNC/linuxcnc/blob/master/.github/scripts/build-package-indep.sh#L8
https://github.com/LinuxCNC/linuxcnc/blob/master/.github/scripts/build-package-arch.sh#L8
so the VERSION file is not changed.
Additionally, change debian/update-dch-from-git to use the VERSION file instead of githelper.