Revert "feat: add bitbake-language-server (neovim#3151)"

This reverts commit 6a6a297.

The official language server for BitBake is called
language-server-bitbake [1] and not bitbake-language-server. Therefore,
it fails to start if using this configuration. Commit 6168237
("feat(bitbake): add language-server-bitbake support (neovim#3199)") added a
configuration where 'cmd' is correctly set to language-server-bitbake.

[1]: https://www.npmjs.com/package/language-server-bitbake