Replace content__wrapper with wrapper

[anselmbradford]

content__wrapper does nothing more than extend wrapper, see https://github.com/cfpb/design-system/blob/6b566bdb7ae2ce4c80a1cd05404bf3ea2e8fe6fa/packages/cfpb-layout/src/cfpb-layout.less#L117

This creates content__wrapper--match-content (since there's a wrapper--match-content class), which is entirely unused. Also, the wrapper is sometimes used outside the context of content block.

This PR replaces instances of content__wrapper with wrapper.

Changes

• Replace content__wrapper with wrapper

How to test this PR

1. The brand header in http://localhost:8000/owning-a-home/explore-rates/ should be unchanged, for example.

[wpears]

Neat!