fix(server): shard the server-test unit job to stop the intermittent crash (#23009)

## Problem

`server-test` fails intermittently: exit 1 with **no `FAIL` line and no
`Test Suites:/Tests:` summary** — the jest run is aborted mid-way,
before the reporter's `onRunComplete`.

## Root cause

The `test` target runs the entire unit suite (~6,600 tests) in **one
in-band jest process on a single runner VM** (`nx.json` sets
`maxWorkers: 1` for the `ci` configuration). A few minutes in, that
process is killed by an **external `SIGKILL`** — confirmed *not* OOM
(~15 GB free at kill time, no cgroup `oom_kill`) and *not* an in-process
crash (a Node diagnostic report armed with `--report-on-fatalerror` +
`--report-uncaught-exception` writes nothing). The whole-run kill is why
it fails intermittently with no summary. `maxWorkers=2` on one VM still
dies, so the threshold is **per-VM**, not per-process.

## Fix

Shard the unit suite across VMs, the same way `server-integration-test`
already does:

- A `twenty-server` `test:ci` target runs jest directly (so `--shard`
forwards) with `dependsOn: ["^build"]` so the workspace deps are built.
- `server-test` becomes a 4-way matrix; each shard runs a quarter of the
suite, well under the kill threshold.
- `ci-server-status-check` already aggregates `server-test`, so required
checks are unchanged.

Also provides two mocks a completed run needs but the SIGKILL had been
masking in `ApplicationRegistrationService.upsertFromCatalog` unit
tests: the `MetricsService` provider and
`applicationRegistrationRepository.createQueryBuilder`.

.github/workflows/ci-server.yaml

@@ -376,6 +376,10 @@ jobs:
     needs: server-build
     timeout-minutes: 30
     runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        shard: [1, 2, 3, 4]
     steps:
       - name: Fetch custom Github Actions and base branch history
         uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4.3.1
@@ -389,11 +393,8 @@ jobs:
           key: ${{ env.SERVER_BUILD_CACHE_KEY }}
       - name: Build twenty-shared
         run: npx nx build twenty-shared
-      - name: Server / Run Tests
-        uses: ./.github/actions/nx-affected
-        with:
-          tag: scope:backend
-          tasks: test
+      - name: Server / Run Tests (shard ${{ matrix.shard }}/4)
+        run: npx nx run twenty-server:test:ci --shard=${{ matrix.shard }}/4
 
   server-integration-test:
     timeout-minutes: 30