Analytics audit: update transcript show event

[SergioEstevao]

📘 Part of: #2628

Update event for transcript search show to match the name in Android

To test

• Start the app
• Ensure you have transcripts logging enabled
• Open a podcast episode with a transcript. Ex: Cautionary Tales podcasts normally have transcript
• Start playing it
• Open the fullscreen player
• Tap on the transcript button
• Tap on Search, and check if the event transcript_search_shown

Checklist

• I have considered if this change warrants user-facing release notes and have added them to CHANGELOG.md if necessary.
• I have considered adding unit tests for my changes.
• I have updated (or requested that someone edit) the spreadsheet to reflect any new or changed analytics.

[dangermattic]

	1 Warning
⚠️	This PR is assigned to the milestone 7.81 ❄️. The due date for this milestone has already passed. Please assign it to a milestone with a later deadline or check whether the release for this milestone has already been finished.

Generated by 🚫 Danger

[danielebogo]

🔵 Tracked: transcript_search_shown ["theme_use_system_settings": true, "theme_light_preference": "default_light", "episode_uuid": "af96b003-2773-4b95-b89f-c423e394e02d", "theme_selected": "default_dark", "podcast_uuid": "ba993300-d71c-0137-1e26-0acc26574db2", "theme_dark_preference": "default_dark"]