MBB: disconnect upon validation failure

Upon seeing NETWORK_STATUS_UNWANTED_DISABLE_AUTOJOIN or
NETWORK_STATUS_UNWANTED_VALIDATION_FAILED during
Make-Before-Break, this means the network is unwanted
by the user or does not have internet. Explicitly trigger
a disconnect.

Bug: 180051267
Test: Using MBB, connect to a network without internet,
      and verify the MBB attempt is aborted.
Test: atest FrameworksWifiTests
Updated-PDD: only add new StaEvent type, covered by existing documentation
Change-Id: I459263a3efa97d2e14a89e43b26295b876c9182c
4 files changed