Use cursor to track updating of registrar sheet

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=138221931

java/google/registry/config/ConfigModule.java

@@ -618,17 +618,6 @@ public final class ConfigModule {
     }
   }
 
-  /**
-   * Amount of time between synchronizations of the Registrar spreadsheet.
-   *
-   * @see google.registry.export.sheet.SyncRegistrarsSheetAction
-   */
-  @Provides
-  @Config("sheetRegistrarInterval")
-  public static Duration provideSheetRegistrarInterval() {
-    return Duration.standardHours(1);
-  }
-
   /**
    * Returns SSH client connection and read timeout.
    *