Previously nested container placeholders (i.e. HTML elements) were
not being fully parsed from translation files. This resulted in bad
translation of messages that contain these placeholders.
Note that this causes the canonical message ID to change for
such messages. Currently all messages generated from
templates use "legacy" message ids that are not affected by
this change, so this fix should not be seen as a breaking change.
Fixes#38422
PR Close#38452