By Nidal al-Mughrabi and Fadi Shana CAIRO/GAZA/JERUSALEM (Reuters) -Israel announced its worst combat losses for more than a month on Wednesday after an ambush in the ruins of Gaza, and faced growing diplomatic isolation as civilian deaths mounted and a humanitarian catastrophe worsened in the Palestinian territory. Intense fighting was under way both north and south Gaza, a day after the United Nations demanded an immediate humanitarian ceasefire. U.S. President Joe Biden said Israel’s “indiscriminate” bombing of civilians was costing international support. Israeli Prime Minister Benjamin Net…