wifi: rtw89: coex: To avoid TWS serials A2DP lag, adjust slot arrangement

The TWS(True wireless stereo) serials Bluetooth audio device need to keep
packet traffic not only with DUT, it also need to synchronize packet with
its assistant earbud. And all the BR/EDR Bluetooth device need to do page
scan to keep re-connect event sensitively between different DUT.
These behavior will make TWS Bluetooth device cost more time slot to keep
the good audio performance. This patch decrease half of Wi-Fi slot(from
40ms to 20ms) in a single cycle. Make the slot more flexible to prevent
audio lag. The single cycle will be shorter, then it will bring some slot
protection cost make Wi-Fi throughput decrease about 5%.

Signed-off-by: Ching-Te Ku <ku920601@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/20250205013233.10945-3-pkshih@realtek.com