[Chore] Textarea Component Updates

[stolve]

What general chore or task would you like to see performed?

The go-form__input textarea component styling updates are as follows:

1. border-color changes to #DEE2E6 for the textarea (this is assumed to take affect automatically after [Chore] Neutral Color Updates #948 )
2. placeholder color change from #B1B1B1 to 75% of #313536
3. border-radius changed to 6px (previously 4px)
4. hover box-shadow color changing from 25% of #d3d3d3 to 80% of #E9ECEF (see [Chore] Neutral Color Updates #948 )
5. hover/focus/active/error state box-shadow spread radius changed from 3px to 4px
6. focus-state border and box-shadow color will be updated to the new galaxy blue (see [Chore] Galaxy Blue Color Update #943 )
7. the error state border and box-shadow color will be updated to the new horizon red (see [Chore] Horizon Red Color Update #946 )
8. the error state font color changed to horizon red
9. disabled/read-only state changes background to #E9ECEF and border to #DEE2E6 (see [Chore] Neutral Color Updates #948 ); apply the not-allowed cursor on hover.
10. disabled state font color changed to 75% of #313536
11. read-only state font color changed to #313536