ref(core): Add debug log when dropping a span via ignoreSpans

[Lms24]

• Emit a debug log when a span matches ignoreSpans
• Adjust the warning when returning null in beforeSendSpan to suggest ignoreSpans instead

closes #17687

[github-actions]

size-limit report 📦

Path	Size	% Change	Change
@sentry/browser	24.22 kB	+0.3%	+71 B 🔺
@sentry/browser - with treeshaking flags	22.74 kB	+0.05%	+10 B 🔺
@sentry/browser (incl. Tracing)	40.23 kB	+0.15%	+59 B 🔺
@sentry/browser (incl. Tracing, Replay)	78.6 kB	+0.06%	+47 B 🔺
@sentry/browser (incl. Tracing, Replay) - with treeshaking flags	68.27 kB	+0.02%	+10 B 🔺
@sentry/browser (incl. Tracing, Replay with Canvas)	83.26 kB	+0.07%	+50 B 🔺
@sentry/browser (incl. Tracing, Replay, Feedback)	95.49 kB	+0.09%	+80 B 🔺
@sentry/browser (incl. Feedback)	40.94 kB	+0.18%	+72 B 🔺
@sentry/browser (incl. sendFeedback)	28.88 kB	+0.23%	+66 B 🔺
@sentry/browser (incl. FeedbackAsync)	33.78 kB	+0.14%	+46 B 🔺
@sentry/react	25.93 kB	+0.23%	+58 B 🔺
@sentry/react (incl. Tracing)	42.23 kB	+0.14%	+57 B 🔺
@sentry/vue	28.71 kB	+0.25%	+70 B 🔺
@sentry/vue (incl. Tracing)	42.04 kB	+0.13%	+53 B 🔺
@sentry/svelte	24.24 kB	+0.22%	+53 B 🔺
CDN Bundle	25.75 kB	+0.05%	+12 B 🔺
CDN Bundle (incl. Tracing)	40.05 kB	+0.03%	+9 B 🔺
CDN Bundle (incl. Tracing, Replay)	76.28 kB	+0.02%	+11 B 🔺
CDN Bundle (incl. Tracing, Replay, Feedback)	81.78 kB	+0.02%	+11 B 🔺
CDN Bundle - uncompressed	75.23 kB	+0.03%	+21 B 🔺
CDN Bundle (incl. Tracing) - uncompressed	118.58 kB	+0.02%	+21 B 🔺
CDN Bundle (incl. Tracing, Replay) - uncompressed	233.71 kB	+0.01%	+21 B 🔺
CDN Bundle (incl. Tracing, Replay, Feedback) - uncompressed	246.47 kB	+0.01%	+21 B 🔺
@sentry/nextjs (client)	44.23 kB	+0.16%	+68 B 🔺
@sentry/sveltekit (client)	40.66 kB	+0.15%	+57 B 🔺
@sentry/node-core	49.96 kB	+0.12%	+55 B 🔺
@sentry/node	151.25 kB	+0.04%	+57 B 🔺
@sentry/node - without tracing	91.86 kB	+0.06%	+53 B 🔺
@sentry/aws-serverless	105.31 kB	+0.06%	+55 B 🔺

View base workflow run

[github-actions]

node-overhead report 🧳

Note: This is a synthetic benchmark with a minimal express app and does not necessarily reflect the real-world performance impact in an application.

Scenario	Requests/s	% of Baseline	Prev. Requests/s	Change %
GET Baseline	9,564	-	9,026	+6%
GET With Sentry	1,428	15%	1,344	+6%
GET With Sentry (error only)	6,188	65%	5,875	+5%
POST Baseline	1,208	-	1,160	+4%
POST With Sentry	561	46%	512	+10%
POST With Sentry (error only)	1,083	90%	1,013	+7%
MYSQL Baseline	3,374	-	3,244	+4%
MYSQL With Sentry	530	16%	372	+42%
MYSQL With Sentry (error only)	2,718	81%	2,615	+4%

View base workflow run

[chargome]

Thanks for adding this!