When Proxy advertising or PB-GATT Advertising Enabled and use a same
advertising sets.
As adv\_start will call multi HCI Command will cause syswork_q yield.
At same time, if another thread(BT RX) all schedule\_send will cause
unable send mesh message, because ADV\_FLAG\_ACTIVE was be set, but
ADV\_FLAG\_PROXY not set currentlly.
Add ADV\_FLAG\_SCHEDULE\_PENDING indicate mesh buf has been pendings
but not scheduled, so when proxy advertising enable, let's take again,
as we can't break or terminated adv\_start, so we must waiting proxy
advertising enabled.
But after https://github.com/zephyrproject-rtos/zephyr/pull/68558
The `k_work_is_pending` always true in `send_pending_adv`, which cause
unable to send more mesh message until more mesh message comming
Signed-off-by: Lingao Meng <menglingao@xiaomi.com>
537d215981