Faster bugreports (6/n)

Posts 'DumpHals' and 'DumpBoard' to the thread pool in the
telephony and wifi mode. A 20% speed is improved in for
telephony mode, and 8% speed is improved in wifi mode.

Bug: 136262402
Test: atest dumpstate_test
Test: atest dumpstate_smoke_test
Test: atest BugreportManagerTestCases
Test: atest CtsBugreportTestCases
Test: Manual enable and disable parallel run
Test: Manual trigger report using hardware key and shortcut
Change-Id: I85abef8a242abf07013cc4eacc342293898082e8