test: Go Debug Adapter Tests is flaky

[hyangah]

The failure rates got worse recently and often block nightly releases.

  1 failing

  1) Go Debug Adapter Tests (legacy)
       disconnect
         should disconnect with multiple disconnectRequests:
     Error: no event 'terminated' received after 20000 ms
  	at Timeout._onTimeout (node_modules/vscode-debugadapter-testsupport/lib/debugClient.js:233:28)
  	at listOnTimeout (internal/timers.js:554:17)
  	at processTimers (internal/timers.js:497:7)

cc @suzmue @quoctruong @polinasok