QBluetoothSocket: use constructor delegation


DRYs the code at source-time and run-time, and makes a following
change to how q_ptr is initialized simpler to implement.

Pick-to: 6.12 6.8
Change-Id: I9247f03ed0795a8a049c9d8045e34a467e635dfc
Reviewed-by: Oliver Wolff <oliver.wolff@qt.io>
commit157dac3a625cdafb7fb3a702eedc4b13a88834ed
parent6f70e2f5f4207add5fbf19703244eee52acf391d
authorMarc Mutz <marc.mutz@qt.io>
committerMarc Mutz <marc.mutz@qt.io>
commit timeMon, 19 Oct 2026 19:56:40 +0000