[show][bgp] Display the Total number of neighbors in the show ip bgp(v6) summary

[arlakshm]

Signed-off-by: Arvindsrinivasan Lakshmi Narasimhan arlakshm@microsoft.com

- What I did
Two minor Fixes to the done

• reset the os environ UTILITIES_UNIT_TESTING_TOPOLOGY multi_asic_intfutil_test after the test is done
• add the line "Total number of neighbors" to the show ip(v6) bgp summary

- How I did it
Update the bgp display function to display the Total number of neighbors

- How to verify it
UT results

============================= test session starts ==============================
platform linux2 -- Python 2.7.16, pytest-3.10.1, py-1.7.0, pluggy-0.8.0
rootdir: /sonic/src/sonic-utilities, inifile: pytest.ini
plugins: cov-2.6.0
collected 143 items

tests/acl_loader_test.py ....                                            [  2%]
tests/aclshow_test.py ...........                                        [ 10%]
tests/bgp_commands_test.py ...                                           [ 12%]
tests/config_mgmt_test.py ....                                           [ 15%]
tests/config_test.py ..                                                  [ 16%]
tests/drops_group_test.py .......                                        [ 21%]
tests/fan_test.py .                                                      [ 22%]
tests/feature_test.py ..........                                         [ 29%]
tests/filter_fdb_entries_test.py ..........                              [ 36%]
tests/gearbox_test.py ..                                                 [ 37%]
tests/interfaces_test.py .............                                   [ 46%]
tests/intfstat_test.py ........                                          [ 52%]
tests/intfutil_test.py ...............                                   [ 62%]
tests/multi_asic_intfutil_test.py .........                              [ 69%]
tests/neighbor_advertiser_test.py .                                      [ 69%]
tests/port2alias_test.py ....                                            [ 72%]
tests/psu_test.py ...                                                    [ 74%]
tests/sflow_test.py ..                                                   [ 76%]
tests/sfp_test.py ...                                                    [ 78%]
tests/show_breakout_test.py ..                                           [ 79%]
tests/show_platform_test.py .                                            [ 80%]
tests/vlan_test.py ............................                          [100%]

- Previous command output (if the output of a command-line utility has changed)

- New command output (if the output of a command-line utility has changed)