Change EppMetric.Builder to use @AutoValue.Builder

Getting rid of builder boilerplate makes my heart sing.  Since we can no
longer @Inject the Builder() constructor, this change adds a provider
in WhiteboxModule that calls a special builderForRequest() factory method,
which gets passed a request ID and Clock and preserves the existing
EppMetric magic that sets the start and end time for you.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=132714432

java/google/registry/module/tools/BUILD

@@ -24,6 +24,7 @@ java_library(
         "//java/google/registry/keyring/api",
         "//java/google/registry/loadtest",
         "//java/google/registry/mapreduce",
+        "//java/google/registry/monitoring/whitebox",
         "//java/google/registry/request",
         "//java/google/registry/request:modules",
         "//java/google/registry/tools/server",