fix metrics test (#916)

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<!-- RECURSEML_SUMMARY:START -->
## High-level PR Summary
This PR fixes a test in the internal metrics endpoint by replacing a
simple wait timer with a more robust retry mechanism. Instead of waiting
for a fixed 3000ms delay to allow for asynchronous event logging, the PR
implements a `Result.retry` approach that attempts to fetch metrics up
to 5 times with exponential backoff, only proceeding when the metrics
response differs from the initial state. This change makes the test more
reliable by ensuring proper test conditions are met before assertions
are made rather than relying on an arbitrary timeout.

⏱️ Estimated Review Time: 5-15 minutes

<details>
<summary>💡 Review Order Suggestion</summary>

| Order | File Path |
|-------|-----------|
| 1 | `apps/e2e/tests/backend/endpoints/api/v1/internal-metrics.test.ts`
|
</details>



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<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

* **Tests**
* Improved backend metrics verification with a retry-based approach to
handle eventual consistency, reducing test flakiness.
* Replaced static waits with structured retries for faster, more
reliable execution.
* Strengthened assertions on metrics fields (e.g., totals and recent
activity) for clearer validation.
* Maintains checks to ensure anonymous users remain excluded from
metrics.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Author: BilalG1

apps/e2e/tests/backend/endpoints/api/v1/internal-metrics.test.ts

@@ -2,6 +2,7 @@ import { wait } from "@stackframe/stack-shared/dist/utils/promises";
 import { expect } from "vitest";
 import { NiceResponse, it } from "../../../../helpers";
 import { Auth, InternalApiKey, Project, backendContext, createMailbox, niceBackendFetch } from "../../../backend-helpers";
+import { Result } from "@stackframe/stack-shared/dist/utils/results";
 
 async function ensureAnonymousUsersAreStillExcluded(metricsResponse: NiceResponse) {
   for (let i = 0; i < 2; i++) {
@@ -125,29 +126,38 @@ it("should exclude anonymous users from metrics", async ({ expect }) => {
     await Auth.Anonymous.signUp();
   }
 
-  await wait(3000);  // the event log is async, so let's give it some time to be written to the DB
+  // the event log is async, so let's give it some time to be written to the DB
+  const result = await Result.retry(async () => {
+    const response = await niceBackendFetch("/api/v1/internal/metrics", { accessType: 'admin' });
+    if (JSON.stringify(response.body) === JSON.stringify(beforeMetrics.body)) {
+      return Result.ok(response);
+    }
+    return Result.error(response);
+  }, 5, { exponentialDelayBase: 200 });
 
-  const response = await niceBackendFetch("/api/v1/internal/metrics", { accessType: 'admin' });
-  expect(beforeMetrics.body).toEqual(response.body);
+  if (result.status === "error") {
+    expect(beforeMetrics.body).toEqual(result.error);
+    throw new Error("Metrics response mismatch, should never be reached");
+  }
 
   // Verify that total_users only counts the 1 regular user, not the anonymous ones
-  expect(response.body.total_users).toBe(1);
+  expect(result.data.body.total_users).toBe(1);
 
   // Verify anonymous users don't appear in recently_registered
-  expect(response.body.recently_registered.length).toBe(1);
-  expect(response.body.recently_registered.every((user: any) => !user.is_anonymous)).toBe(true);
+  expect(result.data.body.recently_registered.length).toBe(1);
+  expect(result.data.body.recently_registered.every((user: any) => !user.is_anonymous)).toBe(true);
 
   // Verify anonymous users don't appear in recently_active
-  expect(response.body.recently_active.every((user: any) => !user.is_anonymous)).toBe(true);
+  expect(result.data.body.recently_active.every((user: any) => !user.is_anonymous)).toBe(true);
 
   // Verify anonymous users aren't counted in daily_users
-  const lastDayUsers = response.body.daily_users[response.body.daily_users.length - 1];
+  const lastDayUsers = result.data.body.daily_users[result.data.body.daily_users.length - 1];
   expect(lastDayUsers.activity).toBe(1);
 
   // Verify users_by_country only includes regular users
-  expect(response.body.users_by_country["US"]).toBe(1);
+  expect(result.data.body.users_by_country["US"]).toBe(1);
 
-  await ensureAnonymousUsersAreStillExcluded(response);
+  await ensureAnonymousUsersAreStillExcluded(result.data);
 });
 
 it("should handle anonymous users with activity correctly", async ({ expect }) => {