Train needs more robust stat functionality on Linux

[tas50]

The current implementation of Stat functionality for Linux in Train is not robust enough to hand new / unknown linux variants.

There is logic at this line to determine if we should use --printf or -c when running the command:

train/lib/train/extras/stat.rb

Line 37 in 6893b8d

format = (backend.os.esx? || backend.os[:name] == "alpine" || backend.os[:name] == "yocto") ? "-c" : "--printf"

This relies on a hard coded list of distros that need -c, which does not work when we encounter a new distro. It's made worse since the failures that occur here are not clear and you'd have to spend the time digging into train to fully understand where the stat command is failing.