Add custom common metric tag feature #312

Job	Run time
set-execution-conditions	8s
build agent and cache	1m 11s
download midwares and cache	14s
Test for agentcore dynamic config (127.0.0.1:8848, NACOS)	57s
Test for agentcore dynamic config (127.0.0.1:2181, ZOOKEEPER)	55s
Test for xds service discovery with only sermant	3m 33s
Test for xds service discovery with spring-client using enovy	3m 19s
Test for xds service discovery with spring-server using envoy	3m 26s
Test for xds router and lb with router plugin (2.0.2.RELEASE, 1.19, Finchley.RELEASE, 4.4, 2.2.0,...	5m 47s
Test for xds router and lb with router plugin (2.1.0.RELEASE, 1.23, Greenwich.RELEASE, 4.4.1, 2.3...	5m 34s
Test for xds router and lb with router plugin (2.2.0.RELEASE, 1.25, Hoxton.RELEASE, 4.5, 2.4.0, 3...	5m 51s
Test for xds router and lb with router plugin (2.3.0.RELEASE, 1.26, Hoxton.RELEASE, 4.5.3, 2.5.0,...	5m 33s
Test for xds router and lb with router plugin (2.4.0, 1.27, 2020.0.0, 4.5.7, 2.6.0, 4.2.2, 4.1.2)	5m 32s
Test for xds router and lb with router plugin (2.6.2, 1.29, 2021.0.0, 4.5.10, 2.7.3, 4.7.2, 4.1.3)	5m 29s
Test for xds router and lb with router plugin (2.7.17, 1.30, 2021.0.3, 4.5.13, 2.7.5, 4.12.0, 4.1.5)	5m 50s
	53m 19s

Provide feedback