[tests] Use build_only=true instead of environments=[]

test_specs are changing to require build_only=true instead of using
environments = [], so adjust accordingly.

Bug: 559278756
Depends-On: fuchsia:Idaee0118dd346e1ae7c54fe6ec8d103a6a6a6964
Change-Id: I15ab00a00ea835ddbf4abdaa51f894f250c62932
Reviewed-on: https://fuchsia-review.googlesource.com/c/third_party/Vulkan-Tools/+/1832810
Reviewed-by: David Fang <fangism@google.com>
Dependencies-Satisfied: cl-deps-checker@fuchsia-internal-service-accts.iam.gserviceaccount.com <cl-deps-checker@fuchsia-internal-service-accts.iam.gserviceaccount.com>
Fuchsia-Auto-Submit: Aaron Wood <aaronwood@google.com>
Reviewed-by: Oliver Newman <olivernewman@google.com>
Commit-Queue: Aaron Wood <aaronwood@google.com>

cube/BUILD.gn

diff --git a/cube/BUILD.gn b/cube/BUILD.gn
index e81f14d..beefdb8 100644
--- a/cube/BUILD.gn
+++ b/cube/BUILD.gn
@@ -43,7 +43,7 @@
   test_components = [ ":vkcube-on-fb-component" ]
   test_specs = {
     # vkcube runs forever, so only run manually.
-    environments = []
+    build_only = true
   }
 }
 
@@ -62,7 +62,7 @@
   test_components = [ ":vkcube-on-fb-protected-component" ]
   test_specs = {
     # vkcube runs forever, so only run manually.
-    environments = []
+    build_only = true
   }
 }
 
@@ -110,7 +110,7 @@
   test_components = [ ":vkcube-skip-present-component" ]
   test_specs = {
     # vkcube runs forever, so only run manually.
-    environments = []
+    build_only = true
   }
 }
 config("cube_config") {