Remove unnecessary "throws" declarations

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=201058582

java/google/registry/tools/ConfirmingCommand.java

@@ -71,7 +71,7 @@ public abstract class ConfirmingCommand implements Command {
    * Perform any post-execution steps (e.g. verifying the result), and return a description String
    * to be printed if non-empty.
    */
-  protected String postExecute() throws Exception {
+  protected String postExecute() {
     return "";
   }