Include more info in host/domain name failures (#1346)

We're seeing some of these in CreateSyntheticHistoryEntriesAction and I
can't tell why from the logs (it doesn't appear to print the repo ID or
domain/host name)

core/src/main/java/google/registry/model/domain/DomainContent.java

@@ -865,7 +865,8 @@ public class DomainContent extends EppResource
     public B setDomainName(String domainName) {
       checkArgument(
           domainName.equals(canonicalizeDomainName(domainName)),
-          "Domain name must be in puny-coded, lower-case form");
+          "Domain name %s not in puny-coded, lower-case form",
+          domainName);
       getInstance().fullyQualifiedDomainName = domainName;
       return thisCastToDerived();
     }

core/src/main/java/google/registry/model/host/HostBase.java

@@ -196,7 +196,8 @@ public class HostBase extends EppResource {
     public B setHostName(String hostName) {
       checkArgument(
           hostName.equals(canonicalizeDomainName(hostName)),
-          "Host name must be in puny-coded, lower-case form");
+          "Host name %s not in puny-coded, lower-case form",
+          hostName);
       getInstance().fullyQualifiedHostName = hostName;
       return thisCastToDerived();
     }

core/src/main/java/google/registry/tools/javascrap/CreateSyntheticHistoryEntriesAction.java

@@ -83,12 +83,12 @@ public class CreateSyntheticHistoryEntriesAction implements Runnable {
   }
 
   /**
-   * The number of shards to run the map-only mapreduce on.
+   * The default number of shards to run the map-only mapreduce on.
    *
-   * <p>This is much lower than the default of 100, or even 10, because we can afford it being slow
+   * <p>This is much lower than the default of 100 because we can afford it being slow and we want
-   * and we want to avoid overloading SQL.
+   * to avoid overloading SQL.
    */
-  private static final int NUM_SHARDS = 3;
+  private static final int NUM_SHARDS = 10;
 
   @Override
   public void run() {

core/src/test/java/google/registry/model/domain/DomainBaseTest.java

@@ -696,7 +696,7 @@ public class DomainBaseTest extends EntityTestCase {
             IllegalArgumentException.class, () -> domain.asBuilder().setDomainName("AAA.BBB"));
     assertThat(thrown)
         .hasMessageThat()
-        .contains("Domain name must be in puny-coded, lower-case form");
+        .isEqualTo("Domain name AAA.BBB not in puny-coded, lower-case form");
   }
 
   @Test
@@ -706,7 +706,7 @@ public class DomainBaseTest extends EntityTestCase {
             IllegalArgumentException.class, () -> domain.asBuilder().setDomainName("みんな.みんな"));
     assertThat(thrown)
         .hasMessageThat()
-        .contains("Domain name must be in puny-coded, lower-case form");
+        .isEqualTo("Domain name みんな.みんな not in puny-coded, lower-case form");
   }
 
   @Test

core/src/test/java/google/registry/model/host/HostResourceTest.java

@@ -200,7 +200,7 @@ class HostResourceTest extends EntityTestCase {
             IllegalArgumentException.class, () -> host.asBuilder().setHostName("AAA.BBB.CCC"));
     assertThat(thrown)
         .hasMessageThat()
-        .contains("Host name must be in puny-coded, lower-case form");
+        .isEqualTo("Host name AAA.BBB.CCC not in puny-coded, lower-case form");
   }
 
   @TestOfyAndSql
@@ -210,7 +210,7 @@ class HostResourceTest extends EntityTestCase {
             IllegalArgumentException.class, () -> host.asBuilder().setHostName("みんな.みんな.みんな"));
     assertThat(thrown)
         .hasMessageThat()
-        .contains("Host name must be in puny-coded, lower-case form");
+        .isEqualTo("Host name みんな.みんな.みんな not in puny-coded, lower-case form");
   }
 
   @TestOfyAndSql