fix(core): Permanent idle timeout cancel finishes the transaction with the last finished child

[krystofwoldrich]

• fixes idle timeout cancel exposed in feat(tracing): Expose cancelIdleTimeout and add option to make it permanent #7236
• this cancellation only worked when no child was active

[github-actions]

size-limit report 📦

Path	Size
@sentry/browser - ES5 CDN Bundle (gzipped + minified)	20.41 KB (-0.01% 🔽)
@sentry/browser - ES5 CDN Bundle (minified)	63.3 KB (0%)
@sentry/browser - ES6 CDN Bundle (gzipped + minified)	18.99 KB (+0.02% 🔺)
@sentry/browser - ES6 CDN Bundle (minified)	56.21 KB (0%)
@sentry/browser - Webpack (gzipped + minified)	20.65 KB (0%)
@sentry/browser - Webpack (minified)	67.44 KB (0%)
@sentry/react - Webpack (gzipped + minified)	20.68 KB (0%)
@sentry/nextjs Client - Webpack (gzipped + minified)	52.1 KB (+0.02% 🔺)
@sentry/browser + @sentry/tracing - ES5 CDN Bundle (gzipped + minified)	33.66 KB (+0.02% 🔺)
@sentry/browser + @sentry/tracing - ES6 CDN Bundle (gzipped + minified)	26.01 KB (+0.04% 🔺)
@sentry/replay ES6 CDN Bundle (gzipped + minified)	43.17 KB (-0.01% 🔽)
@sentry/replay - Webpack (gzipped + minified)	37.19 KB (0%)
@sentry/browser + @sentry/tracing + @sentry/replay - ES6 CDN Bundle (gzipped + minified)	61.31 KB (+0.02% 🔺)
@sentry/browser + @sentry/replay - ES6 CDN Bundle (gzipped + minified)	54.38 KB (0%)

[AbhiPrasad]

Fix makes sense to me 👍