* Saudi British Bank hits 4-year high on Q1 results * Islamic Arab Insurance, Dubai Islamic weigh on Dubai * Egypt market closed due to public holiday By Karina Dsouza and Abinaya Vijayaraghavan April 29 (Reuters) – Abu Dhabi’s stock market slid on Monday, affected by profit-taking and a sell-off in its financial shares, while Saudi Arabia was the only major Gulf market to rise. The Abu Dhabi index lost 0.9 percent in its fourth straight day of declines, with energy firm Dana Gas dropping 4.1 percent and the largest bank in the United Arab Emirates, First Abu Dhabi Bank, losing 1.2 percent. Dana’s stock traded ex-dividend on Thursday and has been sliding since. First Abu Dhabi Bank posted a 3.6 percent rise in