[release-branch.go1.4] all.bash: skip tests by default

The 1.4 tests aren't necessarily supposed to pass.
Disable them by default, to avoid the sort of
unpleasant experience described in #25816.

Change-Id: I763b8e52c8d16f4d9be14ad853df456652e51430
Reviewed-on: https://go-review.googlesource.com/124077
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
3 files changed