Is it obligatory for one who suffers from constant flatulence due to chronic constipation to attempt purification multiple times or to stay in the restroom for a long time before prayer, or is he considered to have continuous flatulence and should not pay attention to the emission of gas during prayer?

If the flatulence stops for a time sufficient for purification (ablution) and prayer, then one must wait to perform the prayer with a valid purification. If the flatulence does not stop for a sufficient time, then one must perform ablution after the prayer time begins, and the emission of flatulence thereafter does not matter as long as no other impurity occurs. You are not required to hold in the flatulence or renew ablution more than once if you suffer from incontinence, nor is it necessary to enter the restroom before purification. It is not permissible to attend the mosque for congregational prayer or Friday prayer if the emission of flatulence harms other worshipers. You will be rewarded if Allah knows the sincerity of your intention.