Improve SHM resilience to crashing participants (backport #3759)

[mergify]

This is an automatic backport of pull request #3759 done by Mergify.
Cherry-pick of 7cf43a6 has failed:

On branch mergify/bp/2.6.x/pr-3759
Your branch is up to date with 'origin/2.6.x'.

You are currently cherry-picking commit 7cf43a62c.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   src/cpp/rtps/DataSharing/DataSharingListener.cpp
	modified:   src/cpp/rtps/DataSharing/DataSharingNotification.hpp
	modified:   src/cpp/rtps/transport/shared_mem/SharedMemManager.hpp

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   src/cpp/rtps/transport/shared_mem/SharedMemGlobal.hpp

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/github/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

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[MiguelCompany]

@richiprosima Please test this

[MiguelCompany]

@richiprosima Please test mac