Bazel: Fix testonly values in BUILD and .bzl files

According to the documentation [1], the expected values for testonly
are True and False. Replace all the current usages of "1" with "True".

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

Change-Id: I89417f6f9d56e126a6b05edeaaa946934799ab23

javatests/com/google/gerrit/util/http/testutil/BUILD

@@ -1,6 +1,6 @@
 java_library(
     name = "testutil",
-    testonly = 1,
+    testonly = True,
     srcs = glob(["**/*.java"]),
     visibility = ["//visibility:public"],
     deps = [