1. solved the previous delayed unit test file size is too large (1.7G+) and the unit test link time is too long problem problems
2. Unify all unit tests into one file to significantly reduce unit test execution time to less than 3 mins
3. temporarily disable stream_load_test.cpp, metrics_action_test.cpp, load_channel_mgr_test.cpp because it will re-implement part of the code and affect other tests
After tablet level metrics is supported, the http metrics API may response
a very large body when a BE holds a large number of tablets, and cause heavy
network traffic.
This patch introduce http content compression to reduce network traffic.
