[BugFix] On pricing configuration prototype naming

| Q	                       | A     |
|--------------------------|------ |
| Bug Fix?        	| yes     |
| New Feature?	| n     |
| BC Breaks?	       | n     |
| Deprecations?	| n     |
| Tests Pass?	       | n     |
| Fixed Tickets	       |        |
| License	               | MIT |
| Doc PR                  |        |

To match with: https://github.com/Sylius/Sylius/blob/master/src/Sylius/Bundle/PricingBundle/Form/EventListener/BuildPriceableFormListener.php#L94