Add bug component as comment to OWNERS

Bug component will be used by TVC and internal tools to file bugs
about CtsPreferenceTestCases.

Test: Tree Hugger
Change-Id: I7f9643fbe442f23301fb79f6e80f1995655a338f
diff --git a/tests/tests/preference/OWNERS b/tests/tests/preference/OWNERS
index 827134e..0ea8182 100644
--- a/tests/tests/preference/OWNERS
+++ b/tests/tests/preference/OWNERS
@@ -1,3 +1,4 @@
+# Bug component: 25700
 lpf@google.com
 pavlis@google.com
 clarabayarri@google.com