[Bug]: Mcp valid but wrong

## What?

There is a Boolean shorthand on entities currently supported in the 2.0 JSON schema:

```json
{
"entities": {
"Products": {
"mcp": true
},
"SensitiveData": {
"mcp": false
}
}
}
```

However, here's the problem:

```json
{
"entities": {
"Products": {
"mcp": {
"dml-tools": true,
"custom-tool": false
}
},
"SensitiveData": {
"mcp": {
"dml-tools": false,
"custom-tool": false
}
}
}
}
```

### This is confusing

It is unclear which sub-property the shorthand is actually toggling.

## Fix

Remove the shorthand on entities, I have already removed it from the docs.

### Not in runtime!

Do not remove the `runtime.mcp.enabled` shorthand, that is still great!