Closes #20291 This PR removes the plain text file association from the default settings, as #21298 added a `LanguageMatcher` for Plain Text files, which now associates "Plain Text" with `txt`-files (see https://github.com/zed-industries/zed/blob/48a79fb22aeeaf23f34c80b1a71692f4bc933d78/crates/language/src/language.rs#L127-L137). Thus, the association via the default settings is not required anymore, which fixes #20291 as described in https://github.com/zed-industries/zed/issues/20291#issuecomment-2500731743 Release Notes: - Fixed default file type associations overriding associations provided by extensions for `txt`-files. Co-authored-by: Peter Tripp <peter@zed.dev>