fix(replay): Ensure we do not set replayId on dsc if replay is disabled

[mydea]

I noticed that we are actually setting the replayId on the DSC even if the replay has stopped. IMHO this doesn't make a lot of sense, so I added this guard.

[github-actions]

size-limit report 📦

Path	Size
@sentry/browser - ES5 CDN Bundle (gzipped + minified)	21.02 KB (-0.01% 🔽)
@sentry/browser - ES5 CDN Bundle (minified)	65.66 KB (0%)
@sentry/browser - ES6 CDN Bundle (gzipped + minified)	19.56 KB (-0.01% 🔽)
@sentry/browser - ES6 CDN Bundle (minified)	58.12 KB (0%)
@sentry/browser - Webpack (gzipped + minified)	21.17 KB (0%)
@sentry/browser - Webpack (minified)	69.07 KB (0%)
@sentry/react - Webpack (gzipped + minified)	21.19 KB (0%)
@sentry/nextjs Client - Webpack (gzipped + minified)	49.03 KB (0%)
@sentry/browser + @sentry/tracing - ES5 CDN Bundle (gzipped + minified)	28.59 KB (0%)
@sentry/browser + @sentry/tracing - ES6 CDN Bundle (gzipped + minified)	26.82 KB (-0.01% 🔽)
@sentry/replay ES6 CDN Bundle (gzipped + minified)	46.21 KB (+0.01% 🔺)
@sentry/replay - Webpack (gzipped + minified)	40.09 KB (+0.02% 🔺)
@sentry/browser + @sentry/tracing + @sentry/replay - ES6 CDN Bundle (gzipped + minified)	65.08 KB (+0.01% 🔺)
@sentry/browser + @sentry/replay - ES6 CDN Bundle (gzipped + minified)	58.05 KB (+0.01% 🔺)