test: make integration tests for the `fields` and `select` suites faster (#15434)

We were restarting and seeding the database in each test. By removing
the `beforeEach` statement, a handful of tests required refactoring to
avoid conflicts with others.

| Suite | Before | After | Improvement | Change |
|-------|--------|-------|-------------|--------|
| **fields** | 11m 22s | ~60s | 91.2% | `beforeEach` seed → `beforeAll`
seed |
| **select** | 4m 3s | ~9s | 96.3% | `beforeEach` create → `beforeAll`
create |
| **TOTAL** | **15m 25s** | **~69s** | **92.5%** | **13.4x faster** |

### Time Saved Per Test Run
- **14 minutes 16 seconds** saved on every test execution
- **From ~3.56s per test → ~0.26s per test** (average across both
suites)