Code Runner Extension doesn't clears the terminal

Issue Type: Bug

Code runner extension has a very help setting called "clearPrevoiusOutput" which is supposed to clear the terminal buffer and then execute the command.
But this doesn't work as expected. Just like the cls command, it only clears the viewport. This causes the text from the prevoius viewport to enter the current viewport which is really annoying.
If you would like to reproduce this at your end, here's how you can do it.
Go to the "settings.json" file and add the following JSON code
"code-runner.clearPrevousOutput": true,
Then try runing a program (say a java program).
You can see that it clears the terminal and it just works fine.
But, when the output of the code goes out of the viewport of the terminal, part of the previous output is still present in the terminal window.
And then if the new output goes out of the viewport once again, even that present in the window and so on. This issue has annoyed me alot and I always have to kill the current terminal and instance everytime I execute my code. Please fix this issue as soon as possible.

Extension version: 0.11.5
VS Code version: Code 1.59.1 (3866c3553be8b268c8a7f8c0482c0c0177aa8bfa, 2021-08-19T11:56:46.957Z)
OS version: Windows_NT x64 10.0.19043
Restricted Mode: No

System Info

|Item|Value|
|---|---|
|CPUs|Intel(R) Core(TM) i3-6006U CPU @ 2.00GHz (4 x 1992)|
|GPU Status|2d_canvas: enabled
gpu_compositing: enabled
multiple_raster_threads: enabled_on
oop_rasterization: enabled
opengl: enabled_on
rasterization: enabled
skia_renderer: enabled_on
video_decode: enabled
vulkan: disabled_off
webgl: enabled
webgl2: enabled|
|Load (avg)|undefined|
|Memory (System)|11.91GB (5.65GB free)|
|Process Argv|--crash-reporter-id 79477b55-3597-4aa7-bcd1-15326f638757|
|Screen Reader|no|
|VM|0%|

A/B Experiments

```
vsliv368:30146709
vsreu685:30147344
python383:30185418
pythonvspyt602:30300191
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pythontb:30283811
pythonptprofiler:30281270
vshan820:30294714
vstes263:30335439
pythondataviewer:30285071
pythonvsuse255:30340121
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pythonvspyt200:30340761
vscextlangct:30333562
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vsccppwtct:30329789
pythonvssor306:30344512
bridge0708:30335490
vstre464:30350172
bridge0723:30353136
javagetstartedc:30351792
vsdyn420:30354109

```