[snmp] Added snmp memory test case

[AndriiLozovyi]

Signed-off-by: Andrii-Yosafat Lozovyi [email protected]

Description of PR

Summary: This PR implements a new test case test_snmp_memory according to the following test plan.
Test should verify that SNMP memory MIB objects are functioning properly.
Fixes # (issue)

Testplan:

• Retrieve facts for a device using SNMP
• Get expected values for a device from system
• Compare that facts received by SNMP are equal to values received from system
• Run script that should slightly load RAM memory
• Retrieve facts for a device using SNMP, verify that SNMP value differs from system data less that 4%

Type of change

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

Approach

What is the motivation for this PR?

This PR is to add a new test case for snmp.

How did you do it?

How did you verify/test it?

Run test on t0 and t1 topo.
snmp/test_snmp_memory.py::test_snmp_memory PASSED
snmp/test_snmp_memory.py::test_snmp_memory_load PASSED

Any platform specific information?

SONiC.master.126-dirty-20210217.092943
Distribution: Debian 10.8
Kernel: 4.19.0-12-2-amd64
Build commit: 6998aef1
Build date: Wed Feb 17 09:42:41 UTC 2021
Platform: x86_64-arista_7170_64c
HwSKU: Arista-7170-64C

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

Any

Documentation

[yxieca]

/azp run

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