ionic build --prod does not create an angular production build

**Description:**
When running `ionic build --prod`, the Angular project is not being built in production mode, but rather in development mode instead.

**Steps to Reproduce:**
Run `ionic build --prod`

**Output:**
```
npm run ionic:build -- --configuration=production --project=app

@0.0.1 ionic:build
npm run build --configuration=production --project=app

@0.0.1 build
ng build
```

**My `ionic info`:**

```
Ionic:

Ionic CLI : 7.0.1 (/Users/twkl/.npm-global/lib/node_modules/@ionic/cli)
Ionic Framework : @ionic/angular 7.0.7
@angular-devkit/build-angular : 16.0.2
@angular-devkit/schematics : 16.0.2
@angular/cli : 16.0.2
@ionic/angular-toolkit : 9.0.0

Capacitor:

Capacitor CLI : 5.0.3
@capacitor/android : not installed
@capacitor/core : 5.0.3
@capacitor/ios : 5.0.3

Utility:

cordova-res : 0.15.4
native-run : 1.7.2

System:

NodeJS : v16.19.1 (/usr/local/bin/node)
npm : 8.19.3
OS : macOS Unknown
```

**Other Information:**
The build process should be running `ng build --configuration=production` instead of just `ng build` as in the output