Move ROID suffix handling from RegistryConfig to ConfigModule

This is the first in a decently long series of commits to delete RegistryConfig
entirely and centralize all configuration in ConfigModule using Dagger. Once
this is done, then the text-based YAML configuration work can begin in earnest.

Note that the configuration settings from TestRegistryConfig will be moving
into ConfigModule.LocalTestConfig. This way they can be referred to in a static
context from test and test utility helpers, rather than having to be injected
everywhere, which we don't typically bother with for tests.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=143473089

java/google/registry/config/RegistryConfig.java

@@ -118,15 +118,6 @@ public interface RegistryConfig {
    */
   public String getGoogleAppsSendFromEmailAddress();
 
-  /**
-   * Returns the roid suffix to be used for the roids of all contacts and hosts.  E.g. a value of
-   * "ROID" would end up creating roids that look like "ABC123-ROID".
-   *
-   * @see <a href="http://www.iana.org/assignments/epp-repository-ids/epp-repository-ids.xhtml">
-   *      Extensible Provisioning Protocol (EPP) Repository Identifiers</a>
-   */
-  public String getContactAndHostRepositoryIdentifier();
-
   /**
    * Returns default WHOIS server to use when {@code Registrar#getWhoisServer()} is {@code null}.
    *