[v9] Remove `autoSessionTracking`

[lforst]

Description

Because autoSessionTracking doesn't make sense across browser and server runtimes we want to remove it in favor of integration based instrumentation. ie. browserSessionIntegration and httpIntegration

Prework was done in #14550

[lforst]

One more todo before closing this. Add migration docs on how to restore behavior if autoSessionTracking: false was configured. nvm I already did that. Goldfish brain :) 😭