fix(intersection_module): remove decel state

[1222-takeshi]

Description

In the intersection module, decel state removed since it only needs to have a GO/STOP state.

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[codecov]

Codecov Report

Merging #1178 (8d76227) into main (68fbe2b) will increase coverage by 0.07%.
The diff coverage is 0.00%.

@@           Coverage Diff            @@
##            main   #1178      +/-   ##
========================================
+ Coverage   9.04%   9.12%   +0.07%     
========================================
  Files       1030    1037       +7     
  Lines      64928   71021    +6093     
  Branches   14256   14946     +690     
========================================
+ Hits        5875    6480     +605     
- Misses     53982   58927    +4945     
- Partials    5071    5614     +543     

Flag	Coverage Δ		*Carryforward flag
differential	5.08% <0.00%> (?)
total	9.12% <0.00%> (+0.08%)	⬆️	Carriedforward from 28a5c4a

*This pull request uses carry forward flags. Click here to find out more.

Impacted Files	Coverage Δ
...e/scene_module/intersection/scene_intersection.hpp	0.00% <ø> (ø)
..._planner/src/scene_module/intersection/manager.cpp	0.00% <ø> (ø)
...c/scene_module/intersection/scene_intersection.cpp	0.00% <0.00%> (ø)
...ule/intersection/scene_merge_from_private_road.cpp	0.00% <0.00%> (ø)
...ity_planner/src/scene_module/intersection/util.cpp	0.00% <0.00%> (ø)
...lude/freespace_planning_algorithms/reeds_shepp.hpp	50.00% <0.00%> (-50.00%)	⬇️
.../src/vehicle/test_vehicle_state_checker_helper.hpp	70.58% <0.00%> (-9.42%)	⬇️
planning/behavior_path_planner/test/input.cpp	60.00% <0.00%> (-7.86%)	⬇️
...tier4_autoware_utils/trajectory/tmp_conversion.hpp	60.00% <0.00%> (-6.67%)	⬇️
...oware_auto_geometry/include/geometry/common_2d.hpp	82.66% <0.00%> (-5.91%)	⬇️
... and 682 more

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[taikitanaka3]

please removeparameters here too later.

autoware.universe/launch/tier4_planning_launch/config/scenario_planning/lane_driving/behavior_planning/behavior_velocity_planner/intersection.param.yaml

Line 5 in 458a32d

decel_velocity: 8.33 # 8.33m/s = 30.0km/h

[soblin]

LGTM