Create a DNS writer that multiplies 10x the domains in the DNS

This is a temporary change used for b/71607306 only, and has TODOs to revert at
every change once the bug is done.

We want to check how Cloud DNS handles large (1M+ domain) zones, especially
during resigning. However, due to a separate bug (b/70980350, and maybe another
one) we can't currently create such a large zone in nomulus within the required
4 day timeframe. The most we managed is 300k domains.

We could wait until the bug is fixed, but if there's a problem with Cloud DNS -
we want to find out as fast as possible. Hence, this CL that allows us to
register 1M domains by creating "just" 100k domains in nomulus.

The CL creates a new "MultiplyingCloudDnsWriter" writer, that when publishing a
domain, pretends that we are publishing 10 domains (with 9 additional
"fictional" domains, that get their Datastore data from the actual domain).

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=180962149

java/google/registry/dns/writer/clouddns/CloudDnsWriterModule.java

@@ -61,6 +61,14 @@ public final class CloudDnsWriterModule {
     return writer;
   }
 
+  // TODO(b/71607306): Remove once large zone resigning is tested
+  @Provides
+  @IntoMap
+  @StringKey(MultiplyingCloudDnsWriter.NAME)
+  static DnsWriter provideMultiplyingWriter(MultiplyingCloudDnsWriter writer) {
+    return writer;
+  }
+
   @Provides
   @IntoSet
   @Named("dnsWriterNames")
@@ -68,6 +76,14 @@ public final class CloudDnsWriterModule {
     return CloudDnsWriter.NAME;
   }
 
+  // TODO(b/71607306): Remove once large zone resigning is tested
+  @Provides
+  @IntoSet
+  @Named("dnsWriterNames")
+  static String provideMultiplyingWriterName() {
+    return MultiplyingCloudDnsWriter.NAME;
+  }
+
   @Provides
   @Named("cloudDns")
   static RateLimiter provideRateLimiter() {