ref: Remove usage of makeMain in tests

[mydea]

This removes most (but not all) usage of makeMain in our own tests.
Some node tests remain for now, most of these will eventually be removed, so I figured no need to change them right now.

[github-actions]

size-limit report 📦

Path	Size
@sentry/browser (incl. Tracing, Replay, Feedback) - Webpack (gzipped)	77.87 KB (+0.08% 🔺)
@sentry/browser (incl. Tracing, Replay) - Webpack (gzipped)	69.11 KB (+0.08% 🔺)
@sentry/browser (incl. Tracing, Replay with Canvas) - Webpack (gzipped)	73.04 KB (+0.08% 🔺)
@sentry/browser (incl. Tracing, Replay) - Webpack with treeshaking flags (gzipped)	62.72 KB (+0.09% 🔺)
@sentry/browser (incl. Tracing) - Webpack (gzipped)	33.3 KB (+0.17% 🔺)
@sentry/browser (incl. browserTracingIntegration) - Webpack (gzipped)	33.21 KB (+0.15% 🔺)
@sentry/browser (incl. Feedback) - Webpack (gzipped)	31.16 KB (0%)
@sentry/browser (incl. sendFeedback) - Webpack (gzipped)	31.16 KB (0%)
@sentry/browser - Webpack (gzipped)	22.43 KB (0%)
@sentry/browser (incl. Tracing, Replay, Feedback) - ES6 CDN Bundle (gzipped)	76.17 KB (+0.08% 🔺)
@sentry/browser (incl. Tracing, Replay) - ES6 CDN Bundle (gzipped)	67.68 KB (+0.07% 🔺)
@sentry/browser (incl. Tracing) - ES6 CDN Bundle (gzipped)	33.65 KB (+0.17% 🔺)
@sentry/browser - ES6 CDN Bundle (gzipped)	24.7 KB (-0.01% 🔽)
@sentry/browser (incl. Tracing, Replay) - ES6 CDN Bundle (minified & uncompressed)	213.03 KB (+0.08% 🔺)
@sentry/browser (incl. Tracing) - ES6 CDN Bundle (minified & uncompressed)	101.65 KB (+0.16% 🔺)
@sentry/browser - ES6 CDN Bundle (minified & uncompressed)	74.01 KB (0%)
@sentry/browser (incl. Tracing) - ES5 CDN Bundle (gzipped)	36.89 KB (+0.17% 🔺)
@sentry/react (incl. Tracing, Replay) - Webpack (gzipped)	69.48 KB (+0.07% 🔺)
@sentry/react - Webpack (gzipped)	22.45 KB (0%)
@sentry/nextjs Client (incl. Tracing, Replay) - Webpack (gzipped)	86.94 KB (-0.3% 🔽)
@sentry/nextjs Client - Webpack (gzipped)	50.11 KB (-0.51% 🔽)
@sentry-internal/feedback - Webpack (gzipped)	17.12 KB (0%)