tarball checksum check - use sha256sum -c

[grooverdan]

There where some failures. Might be a divering implemnation on output but eitherway, sha256sum can check directly without needed to do the comparision in bash.

Adjust path so the tarball can be found by sha256sum.

[RazvanLiviuVarzaru]

This change affects all builders , looks ok but after merge needs a regression test on DEV .
I suggest printing checksum's in standard output so we can track at runtime what is really happening.

[fauust]

Looks OK but yes, it needs testing before merge in prod since it will impact every builder.

[RazvanLiviuVarzaru]

Thanks for the addition Daniel,
after this merge let's schedule a full run on Dev and watch closely how all builders behave.