Hewlett-Packard (HP), the world's largest computer company, has announced plans to cut 24,600 jobs, 7.5 percent of its workforce, to streamline its business.   When HP announced in May that it would acquire technology-services firm Electronic Data Systems Corp. (EDS), layoffs were expected, but not on this scale.    The company plans to shed 24,600 jobs over the next three years, as it combines operations with EDS, whose employees are expected to bear the brunt of the cuts.