chore(web-tracing): remove zone-context-manager

[codecapitano]

Why

Remove ZoneContextManager from the web-tracing instrumentation because it's not needed by Faro's default web-tracing instruments.

If users add more instrumentation manually, they now need to inject the context manager via teh web-tracing config.

  initializeFaro({
    instrumentations: [
      ...getWebInstrumentations({
        captureConsole: true,
      }),
      new TracingInstrumentation({
        contextManager: new ZoneContextManager(),
      }),
    ],
  });

This removes 36.3 kB (minified) | 12.2 kB (minified + gzip) from the bundle
and decreases loading time by 245ms (slow 3g) | 14ms (emerging 4g). https://bundlephobia.com/package/@opentelemetry/[email protected]

`

What

• Remove ZoneContextManager
• add spanProcessor via WebTracerConfig instead of the deprecated provider.addSpanProcessor() function

Links

Checklist

• Tests added
• Changelog updated
• Documentation updated

[codecapitano]

We can close this if we decide to add web-tracing to the default instrumentations.

#971