neovim: tests might fail/hang locally due to shada file

[saidelike]

Note that this should never happen on CI because we run it as a headless on CI and the "enter to continue" message would be skipped. So this could only happen when running tests locally.

The workaround for now is to delete the shada folder as explained in https://vi.stackexchange.com/questions/43006/error-while-reading-shada-file