feat(core): Deprecate Span.instrumenter

[Lms24]

This PR deprecates the instrumenter field on the Span interface and class. The field is not part of the Otel Span API and hence it can't exist publicly on our spans either. After talking with @mydea about the replacement, we can probably replace this with an instanceof check when setting instrumenter on the event in v8. This is breaking though, so for now, we only deprecate it. Users shouldn't need to worry about this field anyway.

[github-actions]

size-limit report 📦

Path	Size
@sentry/browser (incl. Tracing, Replay, Feedback) - Webpack (gzipped)	76.96 KB (-0.03% 🔽)
@sentry/browser (incl. Tracing, Replay) - Webpack (gzipped)	68.35 KB (-0.01% 🔽)
@sentry/browser (incl. Tracing, Replay) - Webpack with treeshaking flags (gzipped)	61.98 KB (-0.02% 🔽)
@sentry/browser (incl. Tracing) - Webpack (gzipped)	32.37 KB (-0.05% 🔽)
@sentry/browser (incl. Feedback) - Webpack (gzipped)	30.97 KB (-0.05% 🔽)
@sentry/browser - Webpack (gzipped)	22.3 KB (-0.05% 🔽)
@sentry/browser (incl. Tracing, Replay, Feedback) - ES6 CDN Bundle (gzipped)	74.61 KB (+0.01% 🔺)
@sentry/browser (incl. Tracing, Replay) - ES6 CDN Bundle (gzipped)	66.24 KB (-0.03% 🔽)
@sentry/browser (incl. Tracing) - ES6 CDN Bundle (gzipped)	32.08 KB (+0.04% 🔺)
@sentry/browser - ES6 CDN Bundle (gzipped)	23.89 KB (-0.03% 🔽)
@sentry/browser (incl. Tracing, Replay) - ES6 CDN Bundle (minified & uncompressed)	208.71 KB (+0.01% 🔺)
@sentry/browser (incl. Tracing) - ES6 CDN Bundle (minified & uncompressed)	96.76 KB (+0.02% 🔺)
@sentry/browser - ES6 CDN Bundle (minified & uncompressed)	71.36 KB (+0.03% 🔺)
@sentry/browser (incl. Tracing) - ES5 CDN Bundle (gzipped)	35.04 KB (-0.02% 🔽)
@sentry/react (incl. Tracing, Replay) - Webpack (gzipped)	68.72 KB (-0.01% 🔽)
@sentry/react - Webpack (gzipped)	22.33 KB (-0.07% 🔽)
@sentry/nextjs Client (incl. Tracing, Replay) - Webpack (gzipped)	85.37 KB (-0.01% 🔽)
@sentry/nextjs Client - Webpack (gzipped)	49.48 KB (-0.04% 🔽)
@sentry-internal/feedback - Webpack (gzipped)	16.99 KB (-0.09% 🔽)