fix(browser): Initialize default integration if defaultIntegrations: undefined

[Lms24]

While working on E2E tests for TwP in meta frameworks, I noticed that we have erroneous logic in the browser SDK init code: If users or our higher-level SDKs pass defaultIntegrations: undefined to the Browser SDK's init options, it deactivates all default integrations. As per our docs, this should only happen if you explicitly pass defaultIntegrations: false.

This is caused by us spreading user-passed options over default SDK options, meaning previously set default options get overridden by users options being explicitly undefined instead of not set.

This PR fixes this by removing the defaultIntegrations key from the user options object before merging the options together. Long-term, we need to fix this properly for all user-passed options. This is blocked on #13262

[github-actions]

size-limit report 📦

Path	Size
@sentry/browser	22.47 KB (+0.07% 🔺)
@sentry/browser (incl. Tracing)	34.26 KB (+0.05% 🔺)
@sentry/browser (incl. Tracing, Replay)	70.31 KB (+0.02% 🔺)
@sentry/browser (incl. Tracing, Replay) - with treeshaking flags	63.64 KB (+0.03% 🔺)
@sentry/browser (incl. Tracing, Replay with Canvas)	74.71 KB (+0.03% 🔺)
@sentry/browser (incl. Tracing, Replay, Feedback)	87.32 KB (+0.02% 🔺)
@sentry/browser (incl. Tracing, Replay, Feedback, metrics)	89.16 KB (+0.02% 🔺)
@sentry/browser (incl. metrics)	26.77 KB (+0.05% 🔺)
@sentry/browser (incl. Feedback)	39.42 KB (+0.06% 🔺)
@sentry/browser (incl. sendFeedback)	27.09 KB (+0.06% 🔺)
@sentry/browser (incl. FeedbackAsync)	31.75 KB (+0.06% 🔺)
@sentry/react	25.24 KB (+0.06% 🔺)
@sentry/react (incl. Tracing)	37.25 KB (+0.05% 🔺)
@sentry/vue	26.62 KB (+0.07% 🔺)
@sentry/vue (incl. Tracing)	36.1 KB (+0.05% 🔺)
@sentry/svelte	22.61 KB (+0.08% 🔺)
CDN Bundle	23.69 KB (+0.07% 🔺)
CDN Bundle (incl. Tracing)	35.93 KB (+0.04% 🔺)
CDN Bundle (incl. Tracing, Replay)	70.36 KB (+0.03% 🔺)
CDN Bundle (incl. Tracing, Replay, Feedback)	75.61 KB (+0.03% 🔺)
CDN Bundle - uncompressed	69.52 KB (+0.11% 🔺)
CDN Bundle (incl. Tracing) - uncompressed	106.43 KB (+0.07% 🔺)
CDN Bundle (incl. Tracing, Replay) - uncompressed	218.27 KB (+0.04% 🔺)
CDN Bundle (incl. Tracing, Replay, Feedback) - uncompressed	231.16 KB (+0.04% 🔺)
@sentry/nextjs (client)	37.1 KB (+0.08% 🔺)
@sentry/sveltekit (client)	34.81 KB (+0.05% 🔺)
@sentry/node	114.77 KB (0%)
@sentry/node - without tracing	89.33 KB (0%)
@sentry/aws-serverless	98.5 KB (0%)