Prior to this fix, the logic to set the right placeholder format for ICUs was a bit incorrect: if there was a nested ICU in one of the root ICU cases, that led to a problem where placeholders in subsequent branches used the wrong ({$placeholder}) format instead of {PLACEHOLDER} one. This commit updates the logic to make sure we properly transform all placeholders even if nested ICUs are present.
PR Close#31516
63e458dd3a