samples: add dut ble only

[ktaborowski]

for testing purposes

CI parameters

Github_actions:
  #(branch, hash, pull/XXX/head)
  NRF_revision: main

  # Do not change after creating PR
  Create_NRF_PR: false
Jenkins:
  test-sdk-sidewalk: bleOnlySidDut

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).

[github-actions]

Sample		diff	used	total
nrf54l15dk/nrf54l15/cpuapp:sample.sidewalk.dut.ble_only	RAM	130.28 KB	130.28 KB	0 B
	ROM	444.3 KB	444.3 KB	0 B
nrf52840dk/nrf52840:sample.sidewalk.dut.ble_only	RAM	131.97 KB	131.97 KB	0 B
	ROM	461.53 KB	461.53 KB	0 B
nrf5340dk/nrf5340/cpuapp:sample.sidewalk.dut.ble_only	RAM	123.4 KB	123.4 KB	0 B
	ROM	384.28 KB	384.28 KB	0 B
nrf54l15dk/nrf54l15/cpuapp/ns:sample.sidewalk.dut.ble_only	RAM	129.5 KB	129.5 KB	0 B
	ROM	394.52 KB	394.52 KB	0 B