Bazel: Fix testonly value in BUILD file

According to the documentation [1], the expected values for testonly
are True and False. Replace the currently used "1" with "True".

[1] https://docs.bazel.build/versions/master/be/common-definitions.html

Change-Id: I824b91afc5cd7e379c1f303464d4342a3b2df014
diff --git a/BUILD b/BUILD
index 59f8856..b6494b5 100644
--- a/BUILD
+++ b/BUILD
@@ -31,7 +31,7 @@
 
 java_library(
     name = "replication_util",
-    testonly = 1,
+    testonly = True,
     srcs = glob(
         ["src/test/java/**/*.java"],
         exclude = ["src/test/java/**/*Test.java"],