im_mad/lib/process_list.rb: guard against cpu_j == 0 and negative delta when process exits #8195

Description
In ProcessList.cpu_info (src/im_mad/remotes/lib/process_list.rb, lines 77-85):

        cpu_j = jiffies - j_ini

        cpu = {}

        pids.each do |pid|
            cpu[pid] = (proc_jiffies(pid) - cpu_ini[pid]) / cpu_j
            cpu[pid] = (cpu[pid] * multiplier).round(2)
        end

Two edge cases occur during host/VM monitoring:

1. If cpu_j <= 0 (for example if /proc/stat fails or returns identical ticks), (proc_jiffies(pid) - cpu_ini[pid]) / cpu_j produces NaN or Infinity, and .round(2) / .to_i raises FloatDomainError.
2. If a monitored process terminates during sleep AVERAGE_SECS, proc_jiffies(pid) rescues Errno::ENOENT and returns 0, making proc_jiffies(pid) - cpu_ini[pid] negative and reporting negative CPU usage.

To Reproduce

1. Call ProcessList.cpu_info when a process exits during sleep AVERAGE_SECS or when cpu_j == 0.
2. Observe negative CPU percentage or FloatDomainError: NaN.

Expected behavior
ProcessList.cpu_info should check cpu_j > 0 and j_end >= cpu_ini[pid], setting cpu[pid] = 0.0 otherwise.

Details

• Affected Component: IM monitoring library (src/im_mad/remotes/lib/process_list.rb)
• Version: master and 7.0.1

Progress Status

• Code committed
• Testing - QA
• Documentation (Release notes - resolved issues, compatibility, known issues)