clang-format resetting default tab size to 8

[pujfei]

Issue Type: Bug

as title, it seems that clang-format would reset default tab size to 8, which is a violation to user privilege if it is truely so.

Extension version: 1.9.0
VS Code version: Code 1.57.1 (507ce72a4466fbb27b715c3722558bb15afa9f48, 2021-06-17T13:28:07.755Z)
OS version: Windows_NT x64 10.0.19043
Restricted Mode: No

System Info

Item	Value
CPUs	Intel(R) Core(TM) i9-10885H CPU @ 2.40GHz (16 x 2400)
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)	31.78GB (21.68GB free)
Process Argv	--crash-reporter-id 4395d9df-7204-44b6-a546-ebbf7177b5c6
Screen Reader	no
VM	0%

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