Reduce NEWMV DRL search limit at speed >= 4

[YixinDu1]

Lower newmv_drl_search_limit from 2 to 1 for speed >= 4.

Anchor: 7837c40
Test condition: CTC, RA, 33 frames, speed 4

RA:

+------------+-------+-------+-------+-------+------+
| Class      |     Y |    Cb |    Cr |  wAvg | Enc% |
+------------+-------+-------+-------+-------+------+
| A1         |  0.07 |  0.18 | -0.04 |  0.06 | 98.2 |
| A2         |  0.04 | -0.02 |  0.10 |  0.04 | 98.3 |
+------------+-------+-------+-------+-------+------+
| Avg w/o B2 |  0.00 |  0.20 |  0.13 |  0.02 | 98.3 |
+------------+-------+-------+-------+-------+------+

STATS_CHANGED

[YixinDu1]

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