[No QA] Simplify capturing performance metrics on release builds

[marcaaron]

Details

It is very difficult to capture reliable performance metrics locally for things like app launch and time to interactive. There are manual ways to check this stuff, but it's very tedious to do e.g. my process has been:

• Hardcode metrics
• Add logs to production server
• Build a release
• Look at the logs and filter

👎

Fixed Issues (Related To)

Fixes https://github.com/Expensify/Expensify/issues/173770
#4027

Tests

1. Set CAPTURE_METRICS=true flag in .env
2. Build an Android release build
3. Sign in
4. Force quit the app and re-open it
5. Verify an alert prints stats
6. Repeat for iOS

QA Steps

None. This feature can only be enabled locally.

Tested On

• Web
• Mobile Web
• Desktop
• iOS
• Android

Screenshots

Android

[OSBotify]

✋ This PR was not deployed to staging yet because QA is ongoing. It will be automatically deployed to staging after the next production release.

[OSBotify]

🚀 Deployed to staging by @timszot in version: 1.0.85-10 🚀

platform	result
🤖 android 🤖	success ✅
🖥 desktop 🖥	success ✅
🍎 iOS 🍎	success ✅
🕸 web 🕸	success ✅

[OSBotify]

🚀 Deployed to production by @roryabraham in version: 1.0.86-11 🚀

platform	result
🤖 android 🤖	success ✅
🖥 desktop 🖥	success ✅
🍎 iOS 🍎	failure ❌
🕸 web 🕸	success ✅