[charts-build-scripts] add make charts validation blocking update on different charts

[nicholasSUSE]

See this PR that is wrong: https://github.com/rancher/charts/pull/4664/commits

The longhorn team used make charts command without specifying the target package as longhorn.
They should have done this:

PACAKGE=longhorn make prepare
PACAKGE=longhorn make patch
make clean
PACAKGE=longhorn make charts

There is probably some development work going on the rancher-monitoring at the same time and since they did not specify the package, the index.yaml for the rancher-monitoring chart got modified.

This is wrong.

Task

Create some sort of GHA validation that detects changes like this and throw an error.