[2.3.x] Only use new string dtype repr for the new (NaN-based) string dtype#62333

mroeschke merged 2 commits intopandas-dev:2.3.xpandas-dev/pandas:2.3.xfrom

jorisvandenbossche:2.3.x-fixup-reprjorisvandenbossche/pandas:2.3.x-fixup-reprCopy head branch name to clipboard