Laws of Mourning When the Deceased Passed Away on Erev Pesach After Noon

If someone's brother passed away and was buried on Erev Pesach after noon, what are the laws regarding the seven and thirty days of mourning?

He does not mourn publicly, but observes mourning privately, and the laws of the seven days of mourning are annulled for him.

The Chochmat Adam wrote in section 169 according to his opinion that one does not mourn on Erev Pesach after noon since it has the status of a festival. "Accordingly, it requires examination if someone died on Erev Pesach after noon, since he does not remove his shoes and does not conduct himself in any manner of mourning, if the festival annuls the decree of the seven days of mourning, even though it can be said that it is not similar to a death during Chol Hamoed, as on Erev Pesach it is only forbidden in matters of privacy, but it is permitted to shave through a non-Jew (Siman 468, section 1), which is not the case now because of mourning it is forbidden even through a non-Jew, although during Chol Hamoed one also does not shave due to the festival and not because of mourning. If so, mourning still exists in terms of shaving on Erev Pesach, and the festival can annul the decree of the seven days of mourning. However, the Taz in Siman 399, section 2, wrote that observing mourning in the form of 'sit and do not act' is not considered mourning. Nevertheless, it seems to me that it is similar to hearing close news on Shabbat before the festival, and yet the festival annuls the decree of the seven days of mourning because he observes matters of privacy, as explained in Siman 399, section 1, and in Siman 402, section 10. If so, here too the festival annuls the decree of the seven days of mourning."