Bluetooth: Controller: Assert when starting periodic advertising right after extended advertising when there is a BIG

[Thalley]

Describe the bug
If there is a BIG created and periodic advertising is started right after extended advertising, there is an assert in the controller that is triggered:

ASSERTION FAIL [id != ((uint8_t)((uint8_t)0 - 1))] @ WEST_TOPDIR/zephyr/subsys/bluetooth/controller/ll_sw/ull_adv_aux.c:3218
@ WEST_TOPDIR/zephyr/subsys/bluetooth/controller/ll_sw/ull_adv_aux.c:3218

To Reproduce
Can be reproduced with #72690

Steps to reproduce the behavior:

1. Remove the k_sleep in start_ext_adv from tests/bsim/bluetooth/host/iso/bis/src/bis_broadcaster.c
2. Build and run tests/bsim/bluetooth/host/iso/bis/tests_scripts/bis.sh
3. See the above assert

Expected behavior
Expect the controller to support starting periodic advertising directly after extended advertising.

Impact
Big annoyance, but can be circumvented with a single k_sleep

Logs and console output
See above

Environment (please complete the following information):

• Commit SHA or Version used Bluetooth: ISO: Support bt_disable #72690 at 59212c1

Additional context
N/A