The 10th anniversary of Massachusetts squash players' subservience to Henry Salaun, the little man whose sceptre is an unerring racquet, was observed yesterday at Harvard's Hemenway Gymnasium. Opening the afternoon program, the 34-year-old Salaun, who ascended to state-wide power in 1951 (and has won three national titles, too) scurried about the court to defeat Henry Foster, 15-2, 10-15, 15-5, 15-9, for his 10th consecutive Middlesex Bowl championship.