tests: handle RPM tilde pre-release versions in NM version parsing

`nm_minor_version` must correctly capture the minor version from
"1.58~rc1" by stripping out "~rc1" before spliiting on ".".

In RPM pre-release versions like release candidates a `~` is used to
represent a version that is smaller than final release.

To properly order these releases, we make "1.58~rc1" equivalent
to 1.57.90 and "1.58~rc2" equivalent to 1.57.91 so that they are
both less than the final release "1.58.0".

Assisted-By: Claude Opus 4.6 <noreply@anthropic.com>
Assisted-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>
Signed-off-by: Rahul Rajesh <rajeshrah22@gmail.com>