fix(motion_utils): check if the buffer is empty

[TomohitoAndo]

Description

In the current implementation, node will die if the data that has old timestamp is passed to the VehicleStopChecker.
This can happen when traffic load increases and message subscribe is delayed.

This is the same issue as this PR.

Tests performed

I added the test and confirmed the program will not die.

Before the change

$ ./build/motion_utils/test_motion_utils --gtest_filter="vehicle_stop_checker*"
Note: Google Test filter = vehicle_stop_checker*
[==========] Running 2 tests from 1 test suite.
[----------] Global test environment set-up.
[----------] 2 tests from vehicle_stop_checker
[ RUN      ] vehicle_stop_checker.isVehicleStopped
fish: Job 1, './build/motion_utils/test_motio…' terminated by signal SIGSEGV (Address boundary error)

After the change

$ ./build/motion_utils/test_motion_utils --gtest_filter="vehicle_stop_checker*"
Note: Google Test filter = vehicle_stop_checker*
[==========] Running 1 test from 1 test suite.
[----------] Global test environment set-up.
[----------] 1 test from vehicle_stop_checker
[ RUN      ] vehicle_stop_checker.isVehicleStopped
[       OK ] vehicle_stop_checker.isVehicleStopped (3044 ms)
[----------] 1 test from vehicle_stop_checker (3044 ms total)

[----------] Global test environment tear-down
[==========] 1 test from 1 test suite ran. (3044 ms total)
[  PASSED  ] 1 test.

Effects on system behavior

Not applicable.

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[codecov]

Codecov Report

Patch coverage: 25.00% and project coverage change: +0.27 🎉

Comparison is base (27fa619) 13.80% compared to head (5869ac9) 14.08%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3883      +/-   ##
==========================================
+ Coverage   13.80%   14.08%   +0.27%     
==========================================
  Files        1391     1523     +132     
  Lines       97408   116829   +19421     
  Branches    28829    36790    +7961     
==========================================
+ Hits        13451    16456    +3005     
- Misses      69501    83299   +13798     
- Partials    14456    17074    +2618     

Flag	Coverage Δ		*Carryforward flag
differential	18.31% <25.00%> (?)
total	13.80% <ø> (ø)		Carriedforward from 27fa619

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

Impacted Files	Coverage Δ
...ls/test/src/vehicle/test_vehicle_state_checker.cpp	18.80% <22.58%> (+0.53%)	⬆️
...motion_utils/src/vehicle/vehicle_state_checker.cpp	73.58% <100.00%> (+2.43%)	⬆️

... and 252 files with indirect coverage changes

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[satoshi-ota]

LGTM