fix(mpc): reset prev value when mpc failed

[TakaHoribe]

Description

Before

The previous steering value in MPC is updated with the actual steering only when getData() failed.
-> when calculateMPC() is failed for any reason other than getData() , the previous steering value is not updated, which is unexpected.

After

The previous steering value in MPC is updated with the actual steering whenever calculateMPC() failed.

Related links

TIERIV'S INTERNAL LINK: https://tier4.atlassian.net/browse/T4PB-26780

Tests performed

Run psim in several paths.

Notes for reviewers

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[takayuki5168]

LGTM

[codecov]

Codecov Report

Patch coverage: 50.00% and no project coverage change.

Comparison is base (0d4e444) 11.86% compared to head (68a1449) 11.87%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3062   +/-   ##
=======================================
  Coverage   11.86%   11.87%           
=======================================
  Files        1333     1333           
  Lines       92786    92787    +1     
  Branches    24649    24651    +2     
=======================================
+ Hits        11011    11015    +4     
+ Misses      70364    70358    -6     
- Partials    11411    11414    +3     

Flag	Coverage Δ		*Carryforward flag
differential	46.56% <50.00%> (?)
total	11.86% <ø> (+<0.01%)	⬆️	Carriedforward from 187d46c

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

Impacted Files	Coverage Δ
..._controller/include/mpc_lateral_controller/mpc.hpp	46.66% <ø> (ø)
control/mpc_lateral_controller/src/mpc.cpp	48.44% <ø> (+0.90%)	⬆️
..._lateral_controller/src/mpc_lateral_controller.cpp	34.76% <50.00%> (+0.10%)	⬆️

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