Collect more CPU/disk/memory metrics

[xueweiz]

This PR adds more CPU/disk/memory metrics:

• cpu_runnable_task_count: helps detecting CPU pressure by measuring the number of "active" tasks on the node
• cpu_usage_time: helps detecting CPU pressure by measuring the CPU usage state breakdown (system v.s. user v.s. irq...)
• disk_operation_count: helps detecting disk IO pressure pattern (together with the 3 metrics below)
• disk_merged_operation_count
• disk_operation_bytes_count
• disk_operation_time
• disk_bytes_used: helps detecting disk space insufficiency
• memory_bytes_used: helps detecting memory pressure via breaking down memory usage by their state (buffer, cache, slab...)
• memory_anonymous_used: helps detecting swap related problems (which could be related to disk IO pressure and memory pressure)
• memory_page_cache_used: helps detecting page cache related problems (slow reads, disk IO pressure, memory pressure)
• memory_unevictable_used: helps detecting swap related problems
• memory_dirty_used: helps detecting filesystem and disk IO pressure

The details are documented in the README for system stats monitor. See a preview here.

[xueweiz]

/assign @wangzhen127
/cc @kewu1992
/cc @vaibhav-rustagi

[k8s-ci-robot]

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/assign @wangzhen127
/cc @kewu1992
/cc @vaibhav-rustagi

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[wangzhen127]

/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: wangzhen127, xueweiz

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[xueweiz]

Thanks a lot for the review Zhen!