Issue #3076054 by godotislate, joaopauloc.dev, smustgrave, nod_, nayana_mvr,...

Issue #3076054 by godotislate, joaopauloc.dev, smustgrave, nod_, nayana_mvr, larowlan, alexpott, lauriii, quietone, benjifisher, anup.singh, bnjmnm: Existing field items should not be validated when adding another item in widget for unlimited cardinality field

(cherry picked from commit 716a1028)