ci: use exit code instead of output text to detect pod trunk push success

[andredestro]

Problem

The publish-ios.sh script was incorrectly reporting a publish failure even when pod trunk push succeeded. This happened because the success check relied on grepping for the word "passed" in the command output — a string that no longer appears in the current CocoaPods trunk response.

As a result, the CI job exited with code 1 and printed an error, despite the pod being successfully published to CocoaPods.

Example of this happening: https://github.com/ionic-team/capacitor-camera/actions/runs/25047098127/job/73365335595

Root Cause

CocoaPods used to include "passed" in its success output. The current output says "successfully published" instead, causing the grep to fail.

Before — fragile: depends on CocoaPods output format:

pod trunk push ... > $LOG_OUTPUT 2>&1
if grep -q "passed" $LOG_OUTPUT; then

Fix

Replace the text-based check with a direct exit code check, which is reliable regardless of CocoaPods output format changes.

After — reliable: checks the actual exit code:

if pod trunk push ... > $LOG_OUTPUT 2>&1; then