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### _Why are the changes needed?_
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BackendService method avg call times and rate. Replace Histograms with Timer to record it. Timer include both Meters and Histograms.
### _How was this patch tested?_
- [x] Add some test cases that check the changes thoroughly including negative and positive cases if possible
- [ ] Add screenshots for manual tests if appropriate
- [x] [Run test](https://kyuubi.readthedocs.io/en/latest/develop_tools/testing.html#running-tests) locally before make a pull request
Closes#1708 from zhenjiaguo/use_timer_for_backend_service.
Closes#1697
3a6af4d3 [zhenjiaguo] comment
0914af2f [zhenjiaguo] use timer to replace histograms
Authored-by: zhenjiaguo <zhenjiaguo@gmail.com>
Signed-off-by: ulysses-you <ulyssesyou@apache.org>
2a7f366b69