[vxlan]Fixing L2MC vlan member caching issue

[dgsudharsan]

What I did
Fixed caching issue when L2MC member is removed. During the L2MC member removal, the local variables are modified but not updated to cache. Since L2MC removal is not updated in cache, the same member being added again will be skipped as duplicate.

Why I did it
To fix the above mentioned issues. Without the fix, the same L2MC member removal and add will not work.

How I verified it
Flapped the remote end point and verified if it L2MC member is created again

Details if related

[dgsudharsan]

The coverage fails because we cannot add test to simulate the SAI failure scenario. This code is used to trigger the orchagent exit when any SAI call fails and this cannot be simulated in the vs.

[prsunny]

Diff coverage reported is for the failure cases which cannot be easily handled by VS tests. Manually verified and functional code has the coverage. Merging bypassing the diff check

Not covered:

                task_process_status handle_status = handleSaiSetStatus(SAI_API_VLAN, status);
                if (handle_status != task_success)
                {
                    m_portList[vlan.m_alias] = vlan;
                    return parseHandleSaiStatusFailure(handle_status);
                }