Shard the RDAP tests

These typically take the longest to complete, so sharding them will make them faster.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=199796400

javatests/google/registry/rdap/BUILD

@@ -40,6 +40,7 @@ java_library(
 GenTestRules(
     name = "GeneratedTestRules",
     medium_tests = ["RdapDomainSearchActionTest"],
+    shard_count = 4,
     test_files = glob(["*Test.java"]),
     deps = [":rdap"],
 )