MT#58934 GitHub issue templates: list architectures as reported via `uname -m`
Architectures like amd64, i386,... are reported by
`dpkg --print-architecture`, though we can't rely on those
since we don't have only Debian based systems.
So switch to the actual output, as provided by `uname -m`.
Don't list options alphabetically though, as x86_64 AKA amd64
should be the most common option, and "other" makes sense to
present as last option.
Change-Id: I2d8a39d9807f0134665d25de6d89c22a4141a4f9