fixup! X neotest/runTestSuite: Tee tested process stdout,stderr to testnode logs incrementally

stderr is unbuffered, but by default stdout is buffered, so if stdout in
turn is redirected to be read by some other logging program, due to
buffering output could be delayed.

Don't delay the output.

go/neo/t/nxd/runTestSuite

@@ -125,6 +125,7 @@ def tee(fin, fout, buf):
             return  # EOF
 
         fout.write(data)
+        fout.flush()
         buf.append(data)