REF: StringArray._from_sequence, use less memory
- [x] closes #35499
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

@ldacey, can you try if this fixes your problem?

CC @simonjayhawkins  