ScanManager Start scan native only for the first client

When gms start a opportunistic scan after a regular scan, it will
trigger a call to the gattclientscannative (true) function.
The Le audio feature on mtk platform modifies the BT stack which
gattclientscannative (true) and gattclientscannative (false) must appear
in pairs, otherwise the ble scan cannot be paused in bt stack.

Bug: 197027791
Tag: #stability
Test: power consumption of ble scan when screen off
Sponsor: jpawlowski@

Signed-off-by: zhoutengteng <zhoutengteng@xiaomi.com>
Change-Id: I4b8796077336a61e826e0b50bb140b3379a0ca9b