[Fix] Update configs to use new nms config style (#1258)

* Update config to use new nms config.

References:
- https://github.com/open-mmlab/mmdetection/pull/4636
- https://github.com/open-mmlab/mmdetection3d/issues/1254
- https://github.com/open-mmlab/mmdetection/issues/5954



* Revert to master-based version and revert incorrect fixes

* Fix missing conflicts

* Adjust incorrect orders of dataset init after resolving conflicts
Co-authored-by: Tai-Wang <tab_wang@outlook.com>

configs/_base_/models/cascade_mask_rcnn_r50_fpn.py

@@ -126,11 +126,10 @@ model = dict(
             pos_weight=-1,
             debug=False),
         rpn_proposal=dict(
-            nms_across_levels=False,
             nms_pre=2000,
             nms_post=2000,
-            max_num=2000,
-            nms_thr=0.7,
+            max_per_img=2000,
+            nms=dict(type='nms', iou_threshold=0.7),
             min_bbox_size=0),
         rcnn=[
             dict(
@@ -187,11 +186,10 @@ model = dict(
         ]),
     test_cfg=dict(
         rpn=dict(
-            nms_across_levels=False,
             nms_pre=1000,
             nms_post=1000,
-            max_num=1000,
-            nms_thr=0.7,
+            max_per_img=1000,
+            nms=dict(type='nms', iou_threshold=0.7),
             min_bbox_size=0),
         rcnn=dict(
             score_thr=0.05,

configs/_base_/models/mask_rcnn_r50_fpn.py

@@ -89,8 +89,8 @@ model = dict(
             nms_across_levels=False,
             nms_pre=2000,
             nms_post=1000,
-            max_num=1000,
-            nms_thr=0.7,
+            max_per_img=1000,
+            nms=dict(type='nms', iou_threshold=0.7),
             min_bbox_size=0),
         rcnn=dict(
             assigner=dict(
@@ -114,8 +114,8 @@ model = dict(
             nms_across_levels=False,
             nms_pre=1000,
             nms_post=1000,
-            max_num=1000,
-            nms_thr=0.7,
+            max_per_img=1000,
+            nms=dict(type='nms', iou_threshold=0.7),
             min_bbox_size=0),
         rcnn=dict(
             score_thr=0.05,

configs/nuimages/htc_without_semantic_r50_fpn_1x_nuim.py

@@ -153,8 +153,8 @@ model = dict(
             nms_across_levels=False,
             nms_pre=2000,
             nms_post=2000,
-            max_num=2000,
-            nms_thr=0.7,
+            max_per_img=2000,
+            nms=dict(type='nms', iou_threshold=0.7),
             min_bbox_size=0),
         rcnn=[
             dict(
@@ -211,8 +211,8 @@ model = dict(
             nms_across_levels=False,
             nms_pre=1000,
             nms_post=1000,
-            max_num=1000,
-            nms_thr=0.7,
+            max_per_img=1000,
+            nms=dict(type='nms', iou_threshold=0.7),
             min_bbox_size=0),
         rcnn=dict(
             score_thr=0.001,