Fix flaky test: AdapterTest.FillShouldAllowRetryLogicProviderToBeInvoked

### Description

The test `AdapterTest.FillShouldAllowRetryLogicProviderToBeInvoked` is intermittently failing in CI pipelines and has been marked as flaky with `[Trait("Category", "flaky")]`.

### Root Cause

The test uses a 1-second `ConnectTimeout` and 1-second `CommandTimeout` with a `WAITFOR DELAY '00:00:02'` query to force timeout retries. This timing-sensitive approach is inherently fragile in CI environments where resource contention can cause variable execution times.

### File

`src/Microsoft.Data.SqlClient/tests/ManualTests/SQL/AdapterTest/AdapterTest.cs`

### Action Needed

- Investigate the root cause of the intermittent failure
- Make the test reliable (e.g. increase timeouts or use a different mechanism to trigger retries)
- Remove the `[Trait("Category", "flaky")]` attribute once stabilized