[ci]: gzip the vm image disk and memdmp (sonic-net#7131)

Signed-off-by: Guohan Lu <[email protected]>

Author: lguohan

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

@@ -49,6 +49,8 @@ steps:
         virsh -c qemu:///system dumpxml ${{ parameters.dut }} > $(Build.ArtifactStagingDirectory)/kvmdump/${{ parameters.dut }}.xml
         img=$(virsh -c qemu:///system domblklist ${{ parameters.dut }} | grep vda | awk '{print $2}')
         cp $img $(Build.ArtifactStagingDirectory)/kvmdump/${{ parameters.dut }}.img
+        gzip $(Build.ArtifactStagingDirectory)/kvmdump/${{ parameters.dut }}.img
+        sudo gzip $(Build.ArtifactStagingDirectory)/kvmdump/${{ parameters.dut }}.memdmp
         virsh -c qemu:///system undefine ${{ parameters.dut }}
     fi