Fix overzealous label data clipping in save_label_data

[ndickson-nvidia]

Changelogs

• val and test stage data was being clipped to the min and max values of the train stage, even when clipping was not enabled. In Graphium 2, clipping is only done when both a min and max clipping value are specified in the normalization options, even though those may not be the values used for clipping if the data range of the column doesn't span the whole clipping range. The behaviour should now match the behaviour of Graphium 2.

---

Checklist:

• Was this PR discussed in an issue? It is recommended to first discuss a new feature into a GitHub issue before opening a PR.
• Add tests to cover the fixed bug(s) or the new introduced feature(s) (if appropriate).
• Update the API documentation is a new function is added, or an existing one is deleted.
• Write concise and explanatory changelogs above.
• If possible, assign one of the following labels to the PR: feature, fix or test (or ask a maintainer to do it for you).

---

discussion related to that PR

[DomInvivo]

Thanks for the fix, you can merge