Enable Intra DIP at all speeds

[urvangjoshi]

A speed feature include_dip_for_top_n_model_rd_pruning was recently added to speed up DIP for for speed >= 1.

Because of this, there is a very small slowdown when using DIP, with a good coding gain at speed >= 3 (where DIP was disabled before).

Anchor commit: 44be072 (Aug 25, 2026)

Speed 4 CTC 33 frames RA:

+---------+--------+-------------+
| Summary |  YUV   |   Enc-time  |
+---------+--------+-------------+
|   A1    | -0.85% |   101.79%   |
|   A2    | -0.53% |   102.00%   |
|Avg wo B2| -0.46% |   102.56%   |
+---------+--------+-------------+

Speed 3 CTC 33 frames RA:

+---------+--------+-------------+
| Summary |  YUV   |   Enc-time  |
+---------+--------+-------------+
|   A1    | -0.76% |   102.47%   |
|   A2    | -0.46% |   103.18%   |
|Avg wo B2| -0.43% |   103.75%   |
+---------+--------+-------------+

STATS_CHANGED for speed >= 3