Auto merge of rust-lang#14799 - mataha:fix/root-in-verbatim-prefix, r=Veykril

Remove root component from patched Windows UNC path prefix

As it shouldn't be there to begin with (per discussion in rust-lang#14689).

Author: bors

crates/rust-analyzer/src/bin/main.rs

@@ -246,7 +246,7 @@ fn patch_path_prefix(path: PathBuf) -> PathBuf {
                         format!("{}:", d.to_ascii_uppercase() as char)
                     }
                     Prefix::VerbatimDisk(d) => {
-                        format!(r"\\?\{}:\", d.to_ascii_uppercase() as char)
+                        format!(r"\\?\{}:", d.to_ascii_uppercase() as char)
                     }
                     _ => return path,
                 };