fix spi classloader #888

Job	Run time
set-execution-conditions	10s
build agent and cache	26s
download midwares and cache	20s
Test for tag transmission grpc	0s
Test for tag transmission httpclientv4	0s
Test for tag transmission httpclientv3	0s
Test for tag transmission okhttp	0s
Test for tag transmission alibabadubbo	0s
Test for tag transmission apachedubbo	0s
Test for tag transmission sofarpc	0s
Test for tag transmission servicecomb	0s
Test for tag transmission config	0s
Test for tag transmission crossthread	0s
Test for tag transmission jdkhttp and jetty	0s
Test for tag transmission kafka	0s
Test for tag transmission rocketmq	0s
Test for tag transmission jdkhttp and tomcat	0s
	56s

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