contrib/rpm: use meson by default for builds on RHEL10
Summary
This MR makes it so that meson is used by default to build the specfile on RHEL 10 and later.
Purpose
As part of our plan to deprecate autotools, we will now be using meson by default to build NM releases on RHEL 10.
Checklist
Please read https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/blob/main/CONTRIBUTING.md before opening the merge request. In particular, check that:
-
the subject for all commits is concise and explicative -
the message for all commits explains the reason for the change -
the source is properly formatted -
any relevant documentation is up to date -
you have added unit tests if applicable -
the NEWS file is updated when the change deserves to be mentioned, for example for new features, behavior changes, API deprecations, etc.