(Reuters) -Recruitment firm Hays on Tuesday forecast lower-than-expected first-half profit and said the short-term outlook will remain challenging amid a hiring slowdown as a weak macroeconomic outlook weighs on global markets. Shares in the FTSE 250 firm fell as much as 19% to a more than three-year low of 87.1 pence, bottoming the mid-cap index. Some of the top UK-listed recruiters in recent times have highlighted the challenging market conditions, with job candidates avoiding the risk of switching jobs and employers offering lower salary hikes amid broader economic uncertainties. “Overall m…