ScaleCapacity properties should use integer instead of string

**Related command**

`az deployment group create`

The issue is related to the `Microsoft.Insights/autoscalesettings` ARM/Bicep resource schema used during Azure deployments.

---

**Is your feature request related to a problem? Please describe.**

The `ScaleCapacity` properties (`minimum`, `maximum`, and `default`) are currently defined as `string`, even though they represent numeric instance counts.

For example:

```bicep
capacity: {
minimum: '1'
maximum: '10'
default: '2'
}
```

This feels unintuitive because these properties always represent numbers rather than arbitrary text. As a result, Bicep cannot provide strong type checking, and the schema allows any string value instead of only valid integer values.

---

**Describe the solution you'd like**

It would be preferable for these properties to use an integer type instead of a string type.

For example:

```bicep
capacity: {
minimum: 1
maximum: 10
default: 2
}
```

Using integers would:

- Better reflect the semantic meaning of these properties.
- Improve type safety.
- Provide better validation during authoring.
- Make the resource schema more consistent with other numeric Azure resource properties.

I understand that changing the existing API version may introduce a breaking change. If so, this could be considered for a future API version.

---

**Describe alternatives you've considered**

The current workaround is to explicitly convert integer values using the `string()` function.

For example:

```bicep
param instanceCount int = 2

resource vmss 'Microsoft.Compute/virtualMachineScaleSets@...' = {
sku: {
capacity: instanceCount
}
}

resource autoscale 'Microsoft.Insights/autoscalesettings@...' = {
properties: {
profiles: [
{
capacity: {
minimum: string(instanceCount)
maximum: string(instanceCount)
default: string(instanceCount)
}
}
]
}
}
```

Although `sku.capacity` can be omitted when autoscale manages the instance count, both `VirtualMachineScaleSets.sku.capacity` and `ScaleCapacity` represent the number of VM instances. However, one uses an `int` while the other uses a `string`, resulting in an inconsistent authoring experience and requiring unnecessary type conversions.

---

**Additional context**

Documentation references:

- Autoscale Settings: https://learn.microsoft.com/en-us/azure/templates/microsoft.insights/autoscalesettings?pivots=deployment-language-bicep#scalecapacity
- Virtual Machine Scale Sets: https://learn.microsoft.com/en-us/azure/templates/microsoft.compute/virtualmachinescalesets?pivots=deployment-language-bicep

The VMSS `sku.capacity` property is defined as an integer, while the Autoscale `ScaleCapacity` properties are defined as strings, despite both representing the number of VM instances.

I'm not sure whether this is a historical design decision or a technical limitation, but aligning these types would make the API more consistent and improve the developer experience.