gatt: Remove confusing GATT_CL_MAX_LCB

This is not needed and was incorrectly used by the srvc_eng
implementation, which is gatt server and not gatt client.

Bug: 325438660
Flag: Exempt, no functional change.
Test: mmm packages/modules/Bluetooth
Test: Manual sanity tests with multiple devices
Change-Id: I47f62e7edd64383bdea7d94ec98f41ef80313f31