### _Why are the changes needed?_
REST frontend protocol was introduced in Kyuubi 1.4.0 https://github.com/apache/kyuubi/pull/1349, more and more users are using REST in recent days, and to simplify the planned Web UI developments, I think we should enable the REST by default for master(1.8.0-SNAPSHOT).
I do not remove the "experiment" because we don't have strong confident to ensure the API stability in this time, I would like to defer it until the community has confident to mark it as stable.
### _How was this patch tested?_
- [ ] 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/master/develop_tools/testing.html#running-tests) locally before make a pull request
Closes#4483 from pan3793/enable-rest.
Closes#4483
66fef0224 [Cheng Pan] http
91a29b453 [Cheng Pan] nit
29a4826da [Cheng Pan] Enable REST frontend protocol in default
Authored-by: Cheng Pan <chengpan@apache.org>
Signed-off-by: Cheng Pan <chengpan@apache.org>
a47bf6e633