fix(nuxt): Allow overwriting server-side `defaultIntegrations`

[github-actions]

Note

The pull request "fix(nuxt): Allow overwriting server-side defaultIntegrations" was created by @s1gr1d but did not reference an issue. Therefore this issue was created for better visibility in external tools like Linear.

There is no reason for spreading the user-provided options before adding the defaultIntegrations. This changes the order to allow overriding and allowing passing defaultIntegrations: false. Also added tests for that

Came up in this review comment of another PR: #18671 (comment)

[linear]

JS-1416