Revert "[spatial svc]Another workaround to avoid using prev_mi"

This reverts commit c113457af9880b8e15a36cdaabfd414d1c245693.

Temporary revert to allow clean revert of another commit.

Change-Id: Ia9b7b755e6c48e1b6e383329f121fef175a24b27
Revert "Move input frame scaling into the recode loop"

This reverts commit 452dc21500a2339ee685cb28efbd2af1b856ea12.

This change has introduced a significant quality regression on content
with forced key frames. (e.g. the YT and yt-hd set). It is most
noticeable in static content where the kf bits dominate. Here, despite
key frames being apparently coded at the same Q, there is a drop in all
metrics of ~20% (e.g clXR and BFa0).

Change-Id: Iba14cc61778c0846fa0a59c33c55a9fc49512cb4
[spatial svc]Another workaround to avoid using prev_mi

We encode a empty invisible frame in front of the base layer frame to
avoid using prev_mi. Since there's a restriction for reference frame
scaling factor, we have to make it smaller and smaller gradually until
its size is 16x16.

Change remerged.

Change-Id: I9efab38bba7da86e056fbe8f663e711c5df38449
Change initialization of static_scene_max_gf_interval.

This removes an unnecessary restriction that causes
a problem (noticed by AWG) when the forced key frame
interval is set to a very small value, such as 10. In this case
we were being forced to code minimal length GF groups.

Change-Id: I76ef5861a09638ff51f61fea02359554184ada53
Merge "Revert "[spatial svc]Another workaround to avoid using prev_mi""
Merge "Revert "Move input frame scaling into the recode loop""
Merge "[spatial svc]Another workaround to avoid using prev_mi"
Merge "Change initialization of static_scene_max_gf_interval."