ref(browser-utils): Align standalone LCP span attribute setting with pageload span LCP attributes

[Lms24]

Small follow-up from #16591: As identified by cursor (lol), our way of setting the lcp.* attributes wasn't 100% aligned with how and when we set these attributes on the pageload span. This PR changes two things:

• only set attributes if the respective LCP entry values are defined
• truncate lcp.url if it is longer than 200 characters
• re-added comments, since we'll likely remove the pageload-based logic at some point
• also add lcp.size if entry.size === 0 (which previously was falsy and hence not added)

[s1gr1d]

Nice!

[github-actions]

size-limit report 📦

Path	Size	% Change	Change
@sentry/browser	23.99 kB	-	-
@sentry/browser - with treeshaking flags	23.76 kB	-	-
@sentry/browser (incl. Tracing)	39.62 kB	+0.07%	+24 B 🔺
@sentry/browser (incl. Tracing, Replay)	77.82 kB	+0.05%	+38 B 🔺
@sentry/browser (incl. Tracing, Replay) - with treeshaking flags	70.9 kB	+0.06%	+39 B 🔺
@sentry/browser (incl. Tracing, Replay with Canvas)	82.54 kB	+0.06%	+46 B 🔺
@sentry/browser (incl. Tracing, Replay, Feedback)	94.7 kB	+0.04%	+36 B 🔺
@sentry/browser (incl. Feedback)	40.75 kB	-	-
@sentry/browser (incl. sendFeedback)	28.7 kB	-	-
@sentry/browser (incl. FeedbackAsync)	33.59 kB	-	-
@sentry/react	25.76 kB	-	-
@sentry/react (incl. Tracing)	41.61 kB	+0.06%	+22 B 🔺
@sentry/vue	28.37 kB	-	-
@sentry/vue (incl. Tracing)	41.41 kB	+0.07%	+25 B 🔺
@sentry/svelte	24.01 kB	-	-
CDN Bundle	25.5 kB	-	-
CDN Bundle (incl. Tracing)	39.63 kB	+0.07%	+24 B 🔺
CDN Bundle (incl. Tracing, Replay)	75.61 kB	+0.03%	+21 B 🔺
CDN Bundle (incl. Tracing, Replay, Feedback)	81.07 kB	+0.03%	+19 B 🔺
CDN Bundle - uncompressed	74.5 kB	-	-
CDN Bundle (incl. Tracing) - uncompressed	117.77 kB	+0.1%	+108 B 🔺
CDN Bundle (incl. Tracing, Replay) - uncompressed	232.07 kB	+0.05%	+108 B 🔺
CDN Bundle (incl. Tracing, Replay, Feedback) - uncompressed	244.89 kB	+0.05%	+108 B 🔺
@sentry/nextjs (client)	43.26 kB	+0.07%	+30 B 🔺
@sentry/sveltekit (client)	40.08 kB	+0.07%	+27 B 🔺
@sentry/node	162.02 kB	-	-
@sentry/node - without tracing	98.64 kB	-	-
@sentry/aws-serverless	124.4 kB	-	-

View base workflow run