fix(ndt_scan_matcher): make regularization process thread safe

[KYabuuchi]

Description

• Made regularization_pose_msg_ptr_array_ thread-safe.
• Modified not to subscribe to regularization_pose when regularization is disabled.

The reason I did not include the regularization pose subscriber in the main_callback_group is so that the regularization process is not neglected even when sensor_callback becomes heavy. Please check the following links for more details:

• https://github.com/tier4/autoware.iv/pull/2372 (INTERNAL LINK)
• feat: separate callback group to execute callbackInitialPose in paral… #153

Tests performed

I checked the below points using logging_simulator.

1. when regularization_enabled in ndt_scan_matcher.param.yaml is false, regularization_pose is not subscribed. Also, localization results are as usual.

2. When regularization_enabled is true, the node subscribes to the regularization_pose. When the logger level is set to DEBUG, the following log is shown on the console.

[ndt_scan_matcher-32] [DEBUG 1699834328.395343191] [localization.pose_estimator.ndt_scan_matcher]: Regularization pose is set to NDT

Effects on system behavior

This does not affect.

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[codecov]

Codecov Report

Attention: 13 lines in your changes are missing coverage. Please review.

Comparison is base (a84c43b) 15.26% compared to head (97e46e9) 15.27%.
Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #5550   +/-   ##
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  Coverage   15.26%   15.27%           
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  Files        1713     1713           
  Lines      118192   118134   -58     
  Branches    37797    37764   -33     
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- Hits        18047    18046    -1     
+ Misses      79595    79538   -57     
  Partials    20550    20550           

Flag	Coverage Δ		*Carryforward flag
differential	3.73% <0.00%> (?)
total	15.27% <ø> (+<0.01%)	⬆️	Carriedforward from 5eb6389

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Files	Coverage Δ
...ion/ndt_scan_matcher/src/ndt_scan_matcher_core.cpp	3.51% <0.00%> (-0.23%)	⬇️

... and 3 files with indirect coverage changes

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[kminoda]

Thank you for the PR 🙏 LGTM except the following minor comment: