[Bluetooth] Remove redundant Destroy* functions

[Bluetooth] Remove redundant Destroy* functions

Destroy* functions from BluetoothGATTServer class were removed, because
they internally destroyed nested GATT objects.
Such behavior is safe, but redundant, because the native methods already
destroy nested objects.
Their usages were replaced by their counterparts from
BluetoothGATTServerService class.

[Verification] The code compiles. Tested in chrome console together with
https://review.tizen.org/gerrit/#/c/platform/core/api/webapi-plugins/+/244481/
No issues observed.

Change-Id: Ied428687fd4467fe9418afa9f87446c3a9b5b147
Signed-off-by: Pawel Wasowski <p.wasowski2@samsung.com>