test: field update access control test times out locally (#15691)

### What

The `ensure field with update access control is readOnly during both
initial load and after saving` e2e test consistently times out when
running locally but passes in CI.

### Why

The test performs 3 saves + 2 reloads, each with 5-second network
polling, plus form validations. This exceeds the default 20-second local
test timeout but fits within CI's 60-second timeout (3x multiplier).

### How

Added `test.setTimeout(TEST_TIMEOUT_LONG)` at the start of the test to
use the extended timeout (same as the `beforeAll` hook)