Fix to buffer alloc for vp9_bitstream_worker_data

The code was using the bitstream_worker_data when it
wasn't allocated for big enough size. This is because
the existing condition was to only re-alloc the
bitstream_worker_data when current dest_size was larger
than the current frame_size. But under resolution change
where frame_size is increased, beyond the current dest_size,
we need to allow re-alloc to the new size.

The existing condition to re-alloc when dest_size is
larger than frame_size (which is not required) is kept
for now.

Also increase the dest_size to account for image format.

Added tests, for both ROW_MT=0 and 1, that reproduce
the failures in the bugs below.

Note: this issue only affects the REALTIME encoding path.

Bug: b/329088759, b/329674887, b/329179808

Change-Id: Icd65dbc5317120304d803f648d4bd9405710db6f
(cherry picked from commit c29e63728316486082dd6083c2062434b441b77d)

• test/encode_api_test.cc[diff]
• vp9/encoder/vp9_bitstream.c[diff]