Instant Blame blocks mainloop on editor change

As written on the mailing list [1], whenever I change the editor there is a delay before I can continue to work, I've nailed it down to the lambda in Git::Internal::GitPluginPrivate::setupInstantBlame(). Approx. one half for GitClient::instance()->getAuthor(workingDirectory.

The other half in Git::Internal::GitPluginPrivate::instantBlame(), as asked I have checked further into the latter. GitClient::instance()->encoding(GitClient::EncodingCommit, workingDirectory);

[1] https://lists.qt-project.org/pipermail/qt-creator/2023-May/009161.html