* [improvement](shutdown) not print thread pool error stack trace when shutdown when thread pool shutdown, should not print error stack trace, it is very confuse. arrow flight server should not call shutdown, if it is not enabled, because it will print error stack. remove service unavailable from thrift because it is useless. Part of this PR need to pick to 2.0 branch. Co-authored-by: yiguolei <yiguolei@gmail.com>