dashboard/app: add default maintainers to email config
dashboard/app: add default maintainers to email config

Crashes without maintainers are nasty. There is no way to do
anything with them without altering the datastore (they are not mailed).

Add DefaultMaintainers to email config.
These addresses are added to all reported bugs as maintainers (e.g. LKML).
One the report is mailed it's possible to CC more people on it.

xairy/syzkaller,google/syzkaller,google/syzkaller,xairy/syzkaller,google/syzkaller,xairy/syzkaller,xairy/syzkaller,google/syzkaller,google/syzkaller,xairy/syzkaller,google/syzkaller,xairy/syzkaller,google/syzkaller,xairy/syzkaller