xds router performance optimization

[daizhenyu]

What type of PR is this?

Refactor.

What this PR does / why we need it?

The code logic of xds router is optimized to improve performance.
The extra CPU usage decreases to 1.5%, and the call delay decreases to 0.1 ms.

Which issue(s) this PR fixes？

Fixes #1680

Does this PR introduce a user-facing change?

No

Checklist

• Make sure there is a GitHub_issue related with this PR before you start working on it.
• Make sure you have squashed your change to one single commit.
• GitHub Actions works fine in this PR.

[codecov]

Codecov Report

Attention: Patch coverage is 35.15625% with 83 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...r/spring/interceptor/OkHttp3ClientInterceptor.java	0.00%	18 Missing ⚠️
...ring/interceptor/HttpAsyncClient4xInterceptor.java	0.00%	15 Missing ⚠️
...terceptor/HttpUrlConnectionConnectInterceptor.java	0.00%	13 Missing ⚠️
...er/spring/interceptor/HttpClient4xInterceptor.java	0.00%	11 Missing ⚠️
...sermant/router/spring/utils/SpringRouterUtils.java	0.00%	10 Missing ⚠️
...io/sermant/router/common/xds/XdsRouterHandler.java	73.91%	5 Missing and 1 partial ⚠️
...io/sermant/router/common/utils/XdsRouterUtils.java	50.00%	2 Missing and 2 partials ⚠️
...eptor/OkHttpClientInterceptorChainInterceptor.java	76.92%	2 Missing and 1 partial ⚠️
...ice/xds/loadbalance/XdsLoadBalanceServiceImpl.java	0.00%	1 Missing ⚠️
...plement/service/xds/route/XdsRouteServiceImpl.java	0.00%	1 Missing ⚠️
... and 1 more

Flag	Coverage Δ	Complexity Δ
unittests	44.17% <35.15%> (-0.02%)	181.00 <0.00> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ	Complexity Δ
...service/xds/discovery/XdsServiceDiscoveryImpl.java	72.34% <100.00%> (+0.60%)	0.00 <0.00> (ø)
...t/router/common/xds/lb/XdsLoadBalancerFactory.java	68.75% <100.00%> (ø)	0.00 <0.00> (ø)
...rmant/router/spring/utils/BaseHttpRouterUtils.java	93.54% <100.00%> (-6.46%)	0.00 <0.00> (ø)
...ice/xds/loadbalance/XdsLoadBalanceServiceImpl.java	87.50% <0.00%> (-12.50%)	0.00 <0.00> (ø)
...plement/service/xds/route/XdsRouteServiceImpl.java	85.71% <0.00%> (-14.29%)	0.00 <0.00> (ø)
...er/spring/interceptor/LoadBalancerInterceptor.java	61.29% <66.66%> (ø)	0.00 <0.00> (ø)
...eptor/OkHttpClientInterceptorChainInterceptor.java	76.31% <76.92%> (+4.22%)	0.00 <0.00> (ø)
...io/sermant/router/common/utils/XdsRouterUtils.java	76.31% <50.00%> (+2.78%)	0.00 <0.00> (ø)
...io/sermant/router/common/xds/XdsRouterHandler.java	78.26% <73.91%> (-3.56%)	0.00 <0.00> (ø)
...sermant/router/spring/utils/SpringRouterUtils.java	22.58% <0.00%> (-3.35%)	0.00 <0.00> (ø)
... and 4 more

... and 2 files with indirect coverage changes