[ci] increase timeout for valgrind job to 240 minutes (#4773)
[ci] increase timeout for valgrind job to 240 minutes (#4773)


henry0312/LightGBM,henry0312/LightGBM,henry0312/LightGBM,microsoft/LightGBM,henry0312/LightGBM,microsoft/LightGBM,henry0312/LightGBM,microsoft/LightGBM,microsoft/LightGBM,microsoft/LightGBM