Run builds and tests quietly in CI

This prevents hundreds of lines of useless logs being created.

Bug: None
Change-Id: I69807c3d9b76e732c7e7a7a86f898ab26a6a6964
Reviewed-on: https://gn-review.googlesource.com/c/gn/+/23221
Commit-Queue: Matt Stark <msta@google.com>
Reviewed-by: Takuto Ikuta <tikuta@google.com>

infra/recipes/gn.py

diff --git a/infra/recipes/gn.py b/infra/recipes/gn.py
index 93c9634..f0e7d94 100644
--- a/infra/recipes/gn.py
+++ b/infra/recipes/gn.py
@@ -264,11 +264,11 @@
 
             # Windows requires the environment modifications when building too.
             api.step('build',
-                     [cipd_dir.join('ninja'), '-C',
+                     [cipd_dir.join('ninja'), '--quiet', '-C',
                       src_dir.join('out')])
 
             if target.is_host:
-              api.step('test', [src_dir.join('out', 'gn_unittests')])
+              api.step('test', [src_dir.join('out', 'gn_unittests'), '--quiet'])
 
               if api.platform.is_linux:
                 with api.context(env={'CLANG_FORMAT': cipd_dir.join('bin', 'clang-format')}):