tests: Increase Kokoro test timeout to 7 hours

Change-Id: I5a334124cc14d7db3a6227981ed46ae0cc80e558
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/54824
Reviewed-by: Bobby Bruce <bbruce@ucdavis.edu>
Maintainer: Bobby Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>
1 file changed