2.11 Release: Parent Information: Minor updates: default RB (no), field validation (missing for one), grammar and punctuation

**Describe the task**
Parent information details section to behave the same way as add dependant

**Acceptance Criteria**
- [ ] No radio buttons selected by default (currently "No" is preselected)
- [ ] Add field validation to first set of radio buttons
- [ ] Update purple banner "parent(s)" to "parent" (each banner is for one parent only similar to the question

Do want the 'x' for add a parent when there is one parent? (Add dependant 'x' acts as a clear button too)

First two ACs may need to be in a separate ticket

**Additional context**

"No" is selected by default

Field validation for first set of radio buttons is missing

Remove (s) off of parent