Add export policy test cases to link bandwidth test

[self-maurya]

No description provided.

[OpenConfigBot]

Pull Request Functional Test Report for #3522 / ed1643a

Virtual Devices

Device	Test	Test Documentation	Job	Raw Log
Arista cEOS		RT-7.5: BGP Policy - Match and Set Link Bandwidth Community	5760d3d0	Log
Cisco 8000E		RT-7.5: BGP Policy - Match and Set Link Bandwidth Community	e5e5bea2	Log
Cisco XRd		RT-7.5: BGP Policy - Match and Set Link Bandwidth Community	3cf28583	Log
Juniper ncPTX		RT-7.5: BGP Policy - Match and Set Link Bandwidth Community	9c187be3	Log
Nokia SR Linux		RT-7.5: BGP Policy - Match and Set Link Bandwidth Community	f9e0b0dd	Log
Openconfig Lemming		RT-7.5: BGP Policy - Match and Set Link Bandwidth Community	56a8f33d	Log

Hardware Devices

Device	Test	Test Documentation	Raw Log
Arista 7808		RT-7.5: BGP Policy - Match and Set Link Bandwidth Community
Cisco 8808		RT-7.5: BGP Policy - Match and Set Link Bandwidth Community
Juniper PTX10008		RT-7.5: BGP Policy - Match and Set Link Bandwidth Community
Nokia 7250 IXR-10e		RT-7.5: BGP Policy - Match and Set Link Bandwidth Community

Help

[coveralls]

Pull Request Test Coverage Report for Build 11511663890

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 55.268%

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Totals
Change from base Build 11502465664:	0.0%
Covered Lines:	1983
Relevant Lines:	3588

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💛 - Coveralls

[rszarecki]

This PR messed up formating of README.md. Can you please fix it.

[dplore]

Is this intended to be a IOSXR specific function? If so, it should be indicated in the function name. They other option I can think of is to have a switch statement inside the function for dut.Vendor with a case for Cisco