Change Cold/Warm App Start span description to Cold/Warm Start

[krystofwoldrich]

📢 Type of change

• Bugfix
• Refactoring

📜 Description

It's a description, no logic should rely on it, but turned out some does. I open this PR on v7 branch since logic depends on it, I consider this a breaking change.

This PR aligns the naming to match the native SDKs.

https://github.com/getsentry/sentry-cocoa/blob/5c3fa88fefada71a9fd8c567cffd03f875dd94c7/Sources/Sentry/SentryBuildAppStartSpans.m#L40-L51

https://github.com/getsentry/sentry-java/blob/main/sentry-android-core/src/main/java/io/sentry/android/core/ActivityLifecycleIntegration.java#L767-L773

💡 Motivation and Context

💚 How did you test it?

ci

📝 Checklist

• I added tests to verify changes
• No new PII added or SDK only sends newly added PII if sendDefaultPII is enabled
• I updated the docs if needed.
• I updated the wizard if needed.
• All tests passing
• No breaking changes

[github-actions]

Android (legacy) Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	529.28 ms	514.23 ms	-15.05 ms
Size	17.75 MiB	20.11 MiB	2.37 MiB

[github-actions]

iOS (legacy) Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	1209.76 ms	1220.20 ms	10.44 ms
Size	2.63 MiB	3.74 MiB	1.11 MiB

[github-actions]

Android (new) Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	405.12 ms	432.57 ms	27.45 ms
Size	7.15 MiB	8.38 MiB	1.23 MiB

[github-actions]

iOS (new) Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	1225.27 ms	1226.80 ms	1.53 ms
Size	3.19 MiB	4.31 MiB	1.12 MiB

[antonis]

LGTM 🚀