add additional dump for timeout

- add sysrq-trigger current tasks dump
- This helps detecting kernel thread stuck in a specific driver

bug: 37573746
Test: python packages/services/Car/tools/bootanalyze/bootanalyze.py -r -c packages/services/Car/tools/bootanalyze/config.yaml -n 2000 -f -e 15 -w 30  -v -a

Change-Id: Icb20b5fba63d601bb937f004f5889a9bc8340b34