refactor: Remove unnecessary branching in run_cli

Merge #2537

Streamlined code flow by removing redundant if/else logic

COPYBARA_INTEGRATE_REVIEW=#2537 from ftnext:refactor-run-cli d799e17
PiperOrigin-RevId: 827153566

Author: ftnext

src/google/adk/cli/cli.py

@@ -183,10 +183,7 @@ async def run_cli(
         content = event.content
         if not content or not content.parts or not content.parts[0].text:
           continue
-        if event.author == 'user':
-          click.echo(f'[user]: {content.parts[0].text}')
-        else:
-          click.echo(f'[{event.author}]: {content.parts[0].text}')
+        click.echo(f'[{event.author}]: {content.parts[0].text}')
 
     await run_interactively(
         root_agent,