Clean up CSS cruft

[anselmbradford]

Describe the bug

Post BEM conversion (see #1919), here is some additional CSS that can be removed:

• a-tagline--xlarge
• content--2-1
• content__wrapper--match-content - this class is being created because content__wrapper extends wrapper, which defines wrapper--match-content.
• content__bleedbar

Some refactoring:

• o-table-wrapper--scrolling should be updated to o-table--scrolling
• o-form--input-w-btn to not be a modifier of o-form (see cfpb-forms: Change o-form__input-w-btn to o-input-w-btn #1933

[anselmbradford]

content__bleedbar removed in #1954
a-tagline--xlarge removed in #1960

[sonnakim]

@anselmbradford will update this issue

[anselmbradford]

content__wrapper--match-content removed in #1997
o-form--input-w-btn removed in #1979

[sonnakim]

@anselmbradford would you mind updating the status of this one?

[anselmbradford]

o-table-wrapper--scrolling renamed in #2068

[anselmbradford]

I'm going to close this. The last item, content--2-1, is only used in BAH/OAH Rate Explorer. We could remove it from the DS and re-create it in BAH, but there's a similar class, content--3-1, which has wider use and it seems better to keep those two together. If Rate Explorer removes content--2-1, we can remove it here.