testing: setBreakpoints tests failing in dlv-dap mode

[hyangah]

Fixing async/await bugs in the test (https://go-review.googlesource.com/c/vscode-go/+/306549) surfaced this issue:

 1) Go Debug Adapter Tests (dlv-dap)
      setBreakpoints
        should set breakpoints during next:

     AssertionError [ERR_ASSERTION]: 'step' == 'next cancelled'
     + expected - actual

     -step
     +next cancelled
     
 	at /workspace/node_modules/vscode-debugadapter-testsupport/lib/debugClient.js:275:20
 	at runMicrotasks (<anonymous>)
 	at processTicksAndRejections (internal/process/task_queues.js:97:5)
 	at async Promise.all (index 1)


 2) Go Debug Adapter Tests (dlv-dap)
      setBreakpoints
        should set breakpoints during step out:

     AssertionError [ERR_ASSERTION]: 'breakpoint' == 'next cancelled'
     + expected - actual

     -breakpoint
     +next cancelled
     
 	at /workspace/node_modules/vscode-debugadapter-testsupport/lib/debugClient.js:275:20
 	at runMicrotasks (<anonymous>)
 	at processTicksAndRejections (internal/process/task_queues.js:97:5)
 	at async Promise.all (index 1)

cc @suzmue

[gopherbot]

Change https://golang.org/cl/306549 mentions this issue: test/integration: disable broken tests