stats: Output new-world stats before legacy stats

stats: Output new-world stats before legacy stats

Now that global stats have been converted to new-style stats, it's
desirable to output them before legacy stats. This ensures that global
statistics (e.g., host_seconds) show up first in the stat file.

Change-Id: Ib099d0152a6612ebbadd234c27f2f3448aef1260
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/35617
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>