Use TRANSPORT_LE for unknown device type

This commit fixes an issue where using BT_TRANSPORT_AUTO
with an unknown device type resulted in
the allocation of a control block for TRANSPORT_AUTO,
preventing callbacks from being invoked after connection.

This change effectively reverts the logic unintentionally
introduced in aosp/3185968, which caused this issue.

Bug: 369765048
Flag: EXEMPT, revert of aosp/3185968
Test: atest GattClientTest
Change-Id: I4858d89ba0390890936dd71955c66793d52085e3