feat(nextjs): Run source map upload in Vercel develop and preview environments

[lforst]

Since with #7427 we don't throw anymore on missing auth tokens it is pretty safe for us to upload source maps for Vercel develop and preview environments now.

[github-actions]

size-limit report 📦

Path	Size
@sentry/browser - ES5 CDN Bundle (gzipped + minified)	20.25 KB (+0.09% 🔺)
@sentry/browser - ES5 CDN Bundle (minified)	62.98 KB (+0.04% 🔺)
@sentry/browser - ES6 CDN Bundle (gzipped + minified)	18.88 KB (+0.06% 🔺)
@sentry/browser - ES6 CDN Bundle (minified)	55.89 KB (+0.05% 🔺)
@sentry/browser - Webpack (gzipped + minified)	20.64 KB (+0.08% 🔺)
@sentry/browser - Webpack (minified)	67.41 KB (+0.04% 🔺)
@sentry/react - Webpack (gzipped + minified)	20.66 KB (+0.08% 🔺)
@sentry/nextjs Client - Webpack (gzipped + minified)	48.55 KB (+0.02% 🔺)
@sentry/browser + @sentry/tracing - ES5 CDN Bundle (gzipped + minified)	27.52 KB (+0.03% 🔺)
@sentry/browser + @sentry/tracing - ES6 CDN Bundle (gzipped + minified)	25.77 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)	61.19 KB (+0.02% 🔺)
@sentry/browser + @sentry/replay - ES6 CDN Bundle (gzipped + minified)	54.37 KB (+0.03% 🔺)