chore: update file headers (#515)

* changes without context

        autosynth cannot find the source of changes triggered by earlier changes in this
        repository, or by version upgrades to tools such as linters.

* chore: modify synth excludes

Co-authored-by: Bu Sun Kim <busunkim@google.com>
Co-authored-by: Bu Sun Kim <8822365+busunkim96@users.noreply.github.com>
diff --git a/synth.py b/synth.py
index 069b214..49bf2dd 100644
--- a/synth.py
+++ b/synth.py
@@ -7,4 +7,11 @@
 # Add templated files
 # ----------------------------------------------------------------------------
 templated_files = common.py_library(unit_cov_level=100, cov_level=100)
-s.move(templated_files / '.kokoro')  # just move kokoro configs
\ No newline at end of file
+s.move(
+    templated_files / ".kokoro",
+    excludes=[
+        ".kokoro/continuous/common.cfg",
+        ".kokoro/presubmit/common.cfg",
+        ".kokoro/build.sh",
+    ],
+)  # just move kokoro configs