tests: adjust stack size for qemu_x86 and mps2_an385's coverage test

for SDK 0.10.0, it consumes more stack size when coverage enabled
on qemu_x86 and mps2_an385 platform, adjust stack size for most of
the test cases, otherwise there will be stack overflow.

Fixes: #14500.

Signed-off-by: Wentong Wu <wentong.wu@intel.com>