feat(nextjs): Be smarter in warning about old ways of init configuration

[lforst]

In theory it is possible that people still have files like sentry.server.config.ts and reference them from instrumentation.ts. In that case we do not want to show the warning about the old way.

[github-actions]

size-limit report 📦

Path	Size
@sentry/browser	21.65 KB (0%)
@sentry/browser (incl. Tracing)	32.67 KB (-0.05% 🔽)
@sentry/browser (incl. Tracing, Replay)	68.01 KB (-0.04% 🔽)
@sentry/browser (incl. Tracing, Replay) - with treeshaking flags	61.41 KB (-0.04% 🔽)
@sentry/browser (incl. Tracing, Replay with Canvas)	72.05 KB (-0.04% 🔽)
@sentry/browser (incl. Tracing, Replay, Feedback)	84.18 KB (-0.03% 🔽)
@sentry/browser (incl. Feedback)	37.69 KB (0%)
@sentry/browser (incl. sendFeedback)	26.21 KB (0%)
@sentry/browser (incl. FeedbackAsync)	30.77 KB (0%)
@sentry/react	24.33 KB (0%)
@sentry/react (incl. Tracing)	35.63 KB (-0.05% 🔽)
@sentry/vue	25.48 KB (0%)
@sentry/vue (incl. Tracing)	34.46 KB (-0.04% 🔽)
@sentry/svelte	21.78 KB (0%)
CDN Bundle	24.03 KB (0%)
CDN Bundle (incl. Tracing)	34.04 KB (-0.05% 🔽)
CDN Bundle (incl. Tracing, Replay)	67.7 KB (-0.05% 🔽)
CDN Bundle (incl. Tracing, Replay, Feedback)	72.82 KB (-0.04% 🔽)
CDN Bundle - uncompressed	70.64 KB (0%)
CDN Bundle (incl. Tracing) - uncompressed	100.93 KB (-0.08% 🔽)
CDN Bundle (incl. Tracing, Replay) - uncompressed	210.54 KB (-0.04% 🔽)
CDN Bundle (incl. Tracing, Replay, Feedback) - uncompressed	223.58 KB (-0.04% 🔽)
@sentry/nextjs (client)	34.86 KB (-0.04% 🔽)
@sentry/sveltekit (client)	33.23 KB (-0.04% 🔽)
@sentry/node	138.72 KB (0%)