IQM Emerald device reports qubitCount=54 but only accepts 49 qubits

### Describe the bug
`AwsDevice.properties.paradigm.qubitCount` for IQM Emerald (`arn:aws:braket:eu-north-1::device/qpu/iqm/Emerald`) reports **54**, but submitting a circuit that uses more than **49** qubits is rejected by the service.

### To reproduce
```python
from braket.aws import AwsDevice
from braket.circuits import Circuit

device = AwsDevice("arn:aws:braket:eu-north-1::device/qpu/iqm/Emerald")
print(device.properties.paradigm.qubitCount) # -> 54

n = 54
ghz = Circuit().h(0)
for i in range(n - 1):
ghz.cnot(i, i + 1)

device.run(ghz, shots=100)
```

### Expected behavior
`qubitCount` should reflect the number of qubits actually usable for task submission (or the discrepancy between physical and usable qubits should be documented / exposed via a separate property).

### Actual behavior
```
botocore.errorfactory.ValidationException: An error occurred (ValidationException) when calling the CreateQuantumTask operation: Used 54 qubits, which is more than the device qubit count of 49
```

### Environment
- `amazon-braket-sdk` 1.121.0
- Python 3.11.6
- macOS (macOS-26.3-arm64)