fix(node-experimental): Make node-fetch support optional

[mydea]

Installing this on Node <18 produces install time errors, as the package is not compatible, e.g.:

npm WARN EBADENGINE Unsupported engine {
npm WARN EBADENGINE   package: '[email protected]',
npm WARN EBADENGINE   required: { node: '>18.0.0' },
npm WARN EBADENGINE   current: { node: 'v16.18.0', npm: '8.19.2' }
npm WARN EBADENGINE }

We already try-catch the setupInstrumentation hook anyhow, so no need to check again here - if this fails we'll just skip running this integration.