Properly disable uneven 4-way partitions for > 270p at speed 1

[urvangjoshi]

This was attempted originally in
#5305, but it was not working as intended, because seq_params.enable_uneven_4way_partitions was set before any change to sf->part_sf.disable_uneven_4way_partitions was made.

We fix this as follows:

Update seq_params.enable_uneven_4way_partitions based on sf->part_sf.disable_uneven_4way_partitions in
av2_set_speed_features_framesize_dependent() before seq_params_locked.

At speed 1, this properly disables uneven 4-way partitions only when resolution is larger than 270p, while keeping them enabled for <= 270p. There is no behavior change for speed 0 (enabled for all resolutions) or speed >= 2 (disabled for all resolutions in framesize_independent).

Also, keep uneven 4-way partitions enabled for screen content at speed 1, as the loss / speed-up ratio is not good enough.

CTC RA 33 frames (Anchor: 4a8df58 + PR #5393):

+---------+--------+-------------+
| Summary |  YUV   |   Enc-time  |
+---------+--------+-------------+
|   A1    |  0.09% |    96.48%   |
|   A2    |  0.03% |    92.85%   |
|Avg wo B2|  0.10% |    92.18%   |
+---------+--------+-------------+

STATS_CHANGED for speed 1