Bluetooth: l2cap: L2CAP/LE/REJ/BI-02-C test failure

[joerchan]

Describe the bug
The L2CAP/LE/REJ/BI-02-C conformance test will fail when enhanced CBFC
has not been selected in the ICS.

The lower tester expects that since the Enhanced CBFC is not supported,
the command L2CAP_CREDIT_BASED_CONNECTION_REQ should be met with an
L2CAP_COMMAND_REJECT_RSP and not an L2CAP_CREDIT_BASED_CONNECTION_RSP.
A clear and concise description of what the bug is.
What have you tried to diagnose or workaround this issue?

To Reproduce
Steps to reproduce the behavior:
Run L2CAP/LE/REJ/BI-02-C with L2CAP Enhanced Credit Based Flow Control unselected in the ICS.

Expected behavior
L2CAP_CREDIT_BASED_CONNECTION_REQ should be answered with L2CAP_CREDIT_BASED_CONNECTION_RSP
The feature should be excludable through Kconfig.

Impact
Bluetooth conformance test failure.

Logs and console output

Environment (please complete the following information):

• OS: Windows
• Toolchain: Zephyr SDK
• Commit SHA or Version used: 2.4.0

Additional context
Add any other context about the problem here.

[joerchan]

Fixed by: #29666