[KYUUBI apache#6165] Add some HttpClient options for EngineUIProxySer…

…vlet

# 🔍 Description
## Issue References 🔗

This pull request fixes apache#6165

## Describe Your Solution 🔧

Add HttpClient options for engine ui proxy servlet.
- idleTimeout
- maxConnections
- maxThreads
- requestBufferSize
- responseBufferSize
- timeout

## Types of changes 🔖

- [ ] Bugfix (non-breaking change which fixes an issue)
- [x] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing functionality to change)

## Test Plan 🧪

#### Behavior Without This Pull Request ⚰️
Engine UI proxy requests with large headers( > 4k) are failed with 500 http status.

#### Behavior With This Pull Request 🎉
Increase the value of `kyuubi.frontend.rest.proxy.jetty.client.requestBufferSize` properly(ex: 5k), request with large header has succeeded with 200 status.

#### Related Unit Tests

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# Checklist 📝

- [x] This patch was not authored or co-authored using [Generative Tooling](https://www.apache.org/legal/generative-tooling.html)

**Be nice. Be informative.**

Closes apache#6192 from minyk/kyuubi-6165.

Closes apache#6165

6ef26aa [minyk] fix kyuubi version of configs
1812a96 [minyk] apply spotless
3527cad [minyk] set initial parameters to the httpclient of proxy servletholder.

Authored-by: minyk <[email protected]>
Signed-off-by: Cheng Pan <[email protected]>