Update domain objects to contain minimum set

We are querying for the entire domain object in NotificationMessage repository. Instead of doing this, try to only query and retain the minimum set of data needed (aggregate root) for the domain object. Look for this ticket in the comments to find the areas that need updating. We want to define a set of [lightweight metrics](<https://docs.sentry.io/product/explore/metrics/>) that SDKs can automatically collect for e.g. framework, language or platform, focusing only on signals that **do NOT overlap with Tracing**. Ideally these metrics should give a quick sense of app or runtime health, … while deeper investigation will still rely on traces or profiles.<br><br>Examples**:** * Node.js runtime metrics (e.g., event loop delay, heap usage) * Prisma-related metrics in Next.js * Mobile CPU / memory usage to help surface potential ANRs or app hangs --- **Candidate Metrics (add more below)** * … *(please also add ideas, questions or examples in comments)*