Increase the percentage of jobs sent to the experimental recipe builders to 25%

Note that on the recipes inline JSON output has been disabled by https://codereview.chromium.org/140463002 ,
which fixed the most likely root cause of latest slowdown.

BUG=317931

Review URL: https://codereview.chromium.org/143963007

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/commit-queue@246138 0039d316-1c4b-4281-b951-d872f2087c98

projects.py

diff --git a/projects.py b/projects.py
index d304dad..20dc5fa 100644
--- a/projects.py
+++ b/projects.py
@@ -459,7 +459,7 @@
     verifiers.append(
         trigger_experimental_try_job.TriggerExperimentalTryJobVerifier(
             context_obj,
-            percentage=0,
+            percentage=0.25,
             try_job_description={
                 'linux_chromium_dbg': ['defaulttests'],
                 'linux_chromium_rel': ['defaulttests'],