Remove deprecated tar exclude functionality

twrpDU::check_skip_dirs() handles skipped folders now. Everywhere
twrpTar::setexcl() is being used to exclude files eventually calls
createTarFork(), which in turn calls Generate_TarList(), which checks
check_skip_dirs().

Change-Id: Ibbc4eb2eb89863ccb2a15f5a3b5092fb10fcbcc0