Disable DoNotMock Error Prone check

Recent Bazel upgrades Error Prone to major version 2.4.0, that is much
stricter now. In addition, starting from guava 29.0-jre, Cache class was
annotated with DoNotMock Error Prone annotation: [1].

Disable the bug pattern, because without using the mock as advertized by
the check would break the corresponding mockito verifications.

[1] https://github.com/google/guava/commit/4eea0f79c27864039a653ec4ca09ef7585e439fc

Change-Id: I1d95daf0fc25b83349d3f3f05c3bb801cffcc3bc

BUILD

diff --git a/BUILD b/BUILD
index c3f5a11..3b896ff 100644
--- a/BUILD
+++ b/BUILD
@@ -25,6 +25,7 @@
 junit_tests(
     name = "high-availability_tests",
     srcs = glob(["src/test/java/**/*.java"]),
+    javacopts = ["-Xep:DoNotMock:OFF"],
     resources = glob(["src/test/resources/**/*"]),
     tags = [
         "high-availability",