ref: Replace global __DEBUG_BUILD__ type with DEBUG_BUILD const in individual packages

[lforst]

Ref getsentry/sentry-capacitor#249

We had a global & ambient type declaration for __DEBUG_BUILD__ in @sentry/types. This caused problems when people included multiple versions of @sentry/types in their builds because such bindings may only be declared once. This seemed to have affected mostly consuming packages that also depended on @sentry/types: getsentry/sentry-capacitor#249

We fix this by just having a constant in each individual package that is equal to __DEBUG_BUILD__ having its ambient declaration only apply locally. We cannot have only one such constant in e.g. @sentry/utils because there could be complications with regard to tree shaking.

[github-actions]

size-limit report 📦

Path	Size
@sentry/browser (incl. Tracing, Replay) - Webpack (gzipped)	65.85 KB (-0.25% 🔽)
@sentry/browser (incl. Tracing, Replay) - Webpack with treeshaking flags (gzipped)	59.45 KB (+5.78% 🔺)
@sentry/browser (incl. Tracing) - Webpack (gzipped)	31.11 KB (-0.27% 🔽)
@sentry/browser - Webpack (gzipped)	21.37 KB (-0.14% 🔽)
@sentry/browser (incl. Tracing, Replay) - ES6 CDN Bundle (gzipped)	62.7 KB (+0.09% 🔺)
@sentry/browser (incl. Tracing) - ES6 CDN Bundle (gzipped)	29.52 KB (+0.19% 🔺)
@sentry/browser - ES6 CDN Bundle (gzipped)	21.6 KB (+0.2% 🔺)
@sentry/browser (incl. Tracing, Replay) - ES6 CDN Bundle (minified & uncompressed)	197.4 KB (+0.07% 🔺)
@sentry/browser (incl. Tracing) - ES6 CDN Bundle (minified & uncompressed)	89.28 KB (+0.15% 🔺)
@sentry/browser - ES6 CDN Bundle (minified & uncompressed)	64.24 KB (+0.19% 🔺)
@sentry/browser (incl. Tracing) - ES5 CDN Bundle (gzipped)	32.17 KB (+0.16% 🔺)
@sentry/react (incl. Tracing, Replay) - Webpack (gzipped)	66.24 KB (-0.29% 🔽)
@sentry/react - Webpack (gzipped)	21.42 KB (-0.15% 🔽)
@sentry/nextjs Client (incl. Tracing, Replay) - Webpack (gzipped)	82.95 KB (-0.26% 🔽)
@sentry/nextjs Client - Webpack (gzipped)	48.2 KB (-0.24% 🔽)
@sentry-internal/feedback - Webpack (gzipped)	16.19 KB (-0.02% 🔽)