[examples] Update example scene of RungeKutta to make it stable

[hugtalbot]

Further to #5030 I thought it would be good to have some regression on RK4.

[ci-depends-on https://github.com/sofa-framework/Regression/pull/71]

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I have read, understand, and agree SOFA Developer Certificate of Origin (DCO).

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Reviewers will merge this pull-request only if

• it builds with SUCCESS for all platforms on the CI.
• it does not generate new warnings.
• it does not generate new unit test failures.
• it does not generate new scene test failures.
• it does not break API compatibility.
• it is more than 1 week old (or has fast-merge label).

[sofabot]

[ci-depends-on] detected during build #1.

To unlock the merge button, you must

• Merge or close Add regression for RungeKutta Regression#71
  For this build, Regression/ExternalProjectConfig.cmake.in will be edited by builders with
  GIT_REPOSITORY https://github.com/sofa-framework/Regression
  GIT_TAG 9f3d7e489f3278b1e885d2345d8c9422c7df68b5

[fredroy]

[ci-build][with-all-tests]

[sofabot]

[ci-depends-on] detected during build #2.

To unlock the merge button, you must

• Merge or close Add regression for RungeKutta Regression#71
  For this build, Regression/ExternalProjectConfig.cmake.in will be edited by builders with
  GIT_REPOSITORY https://github.com/sofa-framework/Regression
  GIT_TAG 9f3d7e489f3278b1e885d2345d8c9422c7df68b5

[sofabot]

[ci-depends-on] detected during build #3.

All dependencies are merged/closed and all ExternalProject pointers are up-to-date. Congrats! 👍