Removed unnecessary style for chartLayout background

The most recent style are in [components/utilities/chartLayout.css](https://github.com/ScottLogic/d3-financial-components/blob/9e7948a1dc0046e8f43b0296d26f9d541e3b0cf7/components/utilities/chartLayout.css).

The styles in [components/utilities/utilities.css](https://github.com/ScottLogic/d3-financial-components/blob/9e7948a1dc0046e8f43b0296d26f9d541e3b0cf7/components/utilities/utilities.css) were overriding these and are no longer required.