[TestGap] New tests to cover VNET route advertisement.

[siqbal1986]

Description of PR

Summary:
Fixes # (issue)
Added new tests to cover the previously untested scenario. These tests create VNET Vxlan ECMP routes and then chekc if they are advertised to the upstream neighbors.

Type of change

• Bug fix
• Testbed and Framework(new/improvement)
• Test case(new/improvement)

Back port request

• 202012
• 202205
• 202305
• 202311
• 202405

Approach

What is the motivation for this PR?

How did you do it?

Create the BGP profile
Create a VNET routes.
check neighbor bgp routes to verify the advertisements.
The following tests are performed for Both V4 and V6 routes.

Step	Goal	Expected results
Create a tunnel route and advertise the tunnel route to all neighbor without community id	BGP	ALL BGP neighbors can recieve the advertised BGP routes
Create a tunnel route and advertise the tunnel route to all neighbor with community id	BGP	ALL BGP neighbors can recieve the advertised BGP routes with community id
Update a tunnel route and advertise the tunnel route to all neighbor with new community id	BGP	ALL BGP neighbors can recieve the advertised BGP routes with new community id
Create a tunnel route and advertise the tunnel route to all neighbor with BGP profile, but create the profile later	BGP	ALL BGP neighbors can recieve the advertised BGP routes without community id first, after the profile table created, the community id would be added and all BGP neighbors can recieve this update and associate the community id with the route
Delete a tunnel route	BGP	ALL BGP neighbors can remove the previously advertised BGP routes
Create 400 tunnel routes and advertise all tunnel routes to all neighbor with community id	BGP scale	ALL BGP neighbors can recieve 400 advertised BGP routes with community id and record the time
Updat BGP_PROFILE_TABLE with new community id for 400 tunnel routes and advertise all tunnel routes to all neighbor with new community id	BGP scale	ALL BGP neighbors can recieve 400 advertised BGP routes with new community id and record the time

How did you verify/test it?

Any platform specific information?

These scale tests are set to un with 400 routes. Altough I have ran these tests with 4k routes without any problem, but that takes the test run time to around 40 minutes.

Supported testbed topology if it's a new test case?

T1 Cisco, T1 Mlnx, VS

Documentation

[mssonicbld]

The pre-commit check detected issues in the files touched by this pull request.
The pre-commit check is a mandatory check, please fix detected issues.

Detailed pre-commit check results:
trim trailing whitespace.................................................Passed
fix end of files.........................................................Passed
check yaml...........................................(no files to check)Skipped
check for added large files..............................................Passed
check python ast.........................................................Passed
flake8...................................................................Failed
- hook id: flake8
- exit code: 1

tests/common/vxlan_ecmp_utils.py:612:12: F632 use ==/!= to compare constant literals (str, bytes, int, float, tuple)

flake8...............................................(no files to check)Skipped
check conditional mark sort..........................(no files to check)Skipped

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