Do not capitalize `$DISTRIBUTION_NAME` in v1-style menuinst

[jaimergp]

Description

Comes from https://github.com/AnacondaRecipes/conda-standalone-feedstock/pull/9#issuecomment-1699488704

Checklist - did you ...

• [x] Add a file to the news directory (using the template) for the next release's release notes?
• [ ] Add / update necessary tests?
• [ ] Add / update outdated documentation?