[apache#5772] fix: missing param <T> (apache#5776)

### What changes were proposed in this pull request?

Missing param `<T>` is added to the `output` method of `Command.java`.

### Why are the changes needed?

Fix: apache#5772

### Does this PR introduce _any_ user-facing change?

No.

### How was this patch tested?
To verify, please run the following command:
```
./gradlew clean build -x test
```
After running this command, the warning `no @param for <T>` will no
longer appear.

clients/cli/src/main/java/org/apache/gravitino/cli/commands/Command.java

@@ -151,6 +151,7 @@ protected <T extends GravitinoClientBase> Builder<T> constructClient(Builder<T>
    * Outputs the entity to the console.
    *
    * @param entity The entity to output.
+   * @param <T> The type of entity.
    */
   protected <T> void output(T entity) {
     if (outputFormat == null) {