chore: change the steps which points to a specific payload to reference variables

IOP_001_01_01 Create OffStreetParking:1

    [Tags]    since_v1.6.1    iop    cnf_01    4_3_3    additive-inclusive    proxy-exclusive    4_3_6    5_6_1

    # Client sends an HTTP POST request to b1 to create the Full version of OffstreetParking:1 (Figure 4.1.1.1-1)

    # Client sends an HTTP POST request to b1 to create the entity defined in ${entity_payload_filename}

    ${response}=    Create Entity    ${entity_payload_filename}    ${entity_id}    broker_url=${b1_url}

    # Agent checks that a success response has been returned

IOP_001_01_02 Create OffStreetParking:2

    [Tags]    since_v1.6.1    iop    cnf_01    4_3_3    additive-inclusive    proxy-exclusive    4_3_6    5_6_1

    # Client sends an HTTP POST request to b1 to create the Full version of OffstreetParking:2 (Figure 4.1.1.1-4)

    # Client sends an HTTP POST request to b1 to create the entity defined in ${entity_payload_filename}

    ${response}=    Create Entity    ${entity_payload_filename}    ${entity_id}    broker_url=${b1_url}

    # Agent checks that a success response has been returned

IOP_001_02_01 Create OffStreetParking:1

    [Tags]    since_v1.6.1    iop    cnf_02    4_3_3    additive-inclusive    proxy-redirect    4_3_6    5_6_1

    # Client sends an HTTP POST request to b1 to create the Full version of OffstreetParking:1 (Figure 4.1.1.1-1)

    # Client sends an HTTP POST request to b1 to create the entity defined in ${entity_payload_filename}

    ${response}=    Create Entity    ${entity_payload_filename}    ${entity_id}    broker_url=${b1_url}

    # Agent checks that a success response has been returned

IOP_001_02_02 Create OffStreetParking:2

    [Tags]    since_v1.6.1    iop    cnf_02    4_3_3    additive-inclusive    proxy-redirect    4_3_6    5_6_1

    # Client sends an HTTP POST request to b1 to create the Full version of OffstreetParking:2 (Figure 4.1.1.1-4)

    # Client sends an HTTP POST request to b1 to create the entity defined in ${entity_payload_filename}

    ${response}=    Create Entity    ${entity_payload_filename}    ${entity_id}    broker_url=${b1_url}

    # Agent checks that a success response has been returned

IOP_001_03_01 Create OffStreetParking:1

    [Tags]    since_v1.6.1    iop    cnf_03    4_3_3    additive-inclusive    additive-auxiliary    4_3_6    5_6_1

    # Client sends an HTTP POST request to b1 to create the Full version of OffstreetParking:1 (Figure 4.1.1.1-3)

    # Client sends an HTTP POST request to b1 to create the entity defined in ${entity_payload_filename}

    ${response}=    Create Entity    ${entity_payload_filename}    ${entity_id}    broker_url=${b1_url}

    # Agent checks that a success response has been returned