Bluetooth: Host: Deprecate BT_BUF_ACL_RX_COUNT symbol

[cvinayak]

Refer to commit zephyrproject-rtos/zephyr@66ff97e69bd

CI parameters

Jenkins:
  test-sdk-sidewalk: master
  # To reconfigure functional tests:
  # use GH labels func-* (default is func-commit)
  # or
  # Use YAML Filters. Helper side to set filters: https://tester-pc.nordicsemi.no:8080/test_mgmt
  # Filters (place copied YAML filters here):
  #  - filter1:
  #     board: nrf52

Description

JIRA ticket:

Self review

• There is no commented code.
• There are no TODO/FIXME comments without associated issue ticket.
• Commits are properly organized.
• Change has been tested.
• Tests were updated (if applicable).