[travis-ci] remove the -test builds from the build list

Change-Id: I4d1df664ad9355f8b3b2bfdea6e3e08f23f71a9f

.travis.yml

@@ -8,10 +8,6 @@ env:
     - PROJECT=magenta-hikey960-arm64
     - PROJECT=magenta-odroidc2-arm64
 
-    # kernel only, no-magenta builds
-    - PROJECT=pc-x86-64-test
-    - PROJECT=qemu-virt-a53-test
-
 sudo: required
 dist: trusty