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
The broker scan node has two tuple descriptors:
One is dest tuple and the other is src tuple.
The src tuple is used to read the lines of the original file,
and the dest tuple is used to save the converted lines.
The preceding filter is executed on the src tuple, so src tuple descriptor should be used
to initialize the filter expression
