### _Why are the changes needed?_
https://kyuubi.apache.org/docs/latest/deployment/settings.html
The configuration parameters in the document are too long and a newline is inserted(`<br/>`), which makes it difficult to search.
And if the user copies the configuration parameters, it may become several lines.
Use `<code>` to replace `<br/>`.
https://github.com/apache/incubator-kyuubi/issues/1889
### _How was this patch tested?_
- [x] Add some test cases that check the changes thoroughly including negative and positive cases if possible
- [x] Add screenshots for manual tests if appropriate
- [ ] [Run test](https://kyuubi.apache.org/docs/latest/develop_tools/testing.html#running-tests) locally before make a pull request
Closes#1890 from cxzl25/KYUUBI-1889.
Closes#1889
765b0622 [sychen] format metrics.md
abeb0601 [sychen] add newline
28865ad7 [sychen] increase max width
2f9c7e05 [sychen] use <code>
Authored-by: sychen <sychen@trip.com>
Signed-off-by: ulysses-you <ulyssesyou@apache.org>
677e2a40ab