@Kiran_25 

try this optimized code

(function executeRule(current, previous /*null when async*/) {
    var businessApplicationSteward = current.getValue('u_cmdb_data_steward');
    var businessApplicationStewardName = current.u_cmdb_data_steward.name+"";
    var technicalApplicationOwner = current.getValue('u_custodian');
    var technicalApplicationOwnerName = current.u_custodian.name+"";
    var userID = gs.getUserID();

    function note(field, stewardText, ownerText) {
        if (current[field].changes()) {
            if (userID == businessApplicationSteward) {
                current.work_notes = stewardText + businessApplicationStewardName;
            } else if (userID == technicalApplicationOwner) {
                current.work_notes = ownerText + technicalApplicationOwnerName;
            } else if (gs.hasRole('architecture_domain_admin') || gs.hasRole('architecture_domain_manager')) {
                current.work_notes = "The " + field + " field has been updated by " + gs.getUserDisplayName() + ".";
            }
        }
    }

    note('u_business_application_type', 'The Business Application Type field has been updated by the Technical owner representative ', 'The Business Application Type field has been updated by the Technical Owner ');
    note('short_description', 'The Description field has been updated by the Technical owner representative ', 'The Description field has been updated by the Technical Owner ');
    note('u_end_date', 'The End Date field has been updated by the Technical owner representative ', 'The End Date field has been updated by the Technical Owner ');
    note('u_new_application_reason', 'The New Application Reason field has been updated by the Technical owner representative ', 'The New Application Reason field has been updated by the Technical Owner ');
    note('u_primary_capability', 'The Primary Capability field has been updated by the Technical owner representative ', 'The Primary Capability field has been updated by the Technical Owner ');
    note('start_date', 'The Start Date field has been updated by the Technical owner representative ', 'The Start Date field has been updated by the Technical Owner ');
    note('u_strategic_status', 'The Strategic Status field has been updated by the Technical owner representative ', 'The Strategic Status field has been updated by the Technical Owner ');
    note('u_target_hosting_type_ref', 'The Target Hosting Type field has been updated by the Technical owner representative ', 'The Target Hosting Type field has been updated by the Technical Owner ');

})(current, previous);

If my response helped please mark it correct and close the thread so that it benefits future readers.