Make the "t0-sonic" check of PR testing optional (#5577)

What is the motivation for this PR?
The "t0-sonic" check of PR testing is still unstable. This check should not block PR merging.

How did you do it?
This change added code to make check results of "t0-sonic" optional.

Signed-off-by: Xin Wang <xiwang5@microsoft.com>

.azure-pipelines/run-test-template.yml

@@ -59,6 +59,8 @@ steps:
     parent_dir=$(basename $PWD)
     docker exec sonic-mgmt-2 bash -c "/var/src/$parent_dir/tests/kvmtest.sh -en -T ${{ parameters.tbtype }} -d /var/src/$parent_dir ${{ parameters.tbname }} ${{ parameters.dut }} ${{ parameters.section }}"
   displayName: "Run tests"
+  ${{ if eq(parameters.tbtype, 't0-sonic') }}:
+      continueOnError: true
 
 - script: |
     # save dut state if test fails