fix(crate_universe): fix OUTPUT_BASE env var value format in crates_vendor

The OUTPUT_BASE env var override inserted
`format!("output_base: {}", path)` as the HashMap value. However, the
`bazel info` output parser splits each line on `:` and stores only the
part after the colon as the value:

    let (k, v) = line.split_at(line.find(':')?);
    Ok((k.to_string(), (v[1..]).trim().to_string()))

So for `bazel info` output like "output_base: /data/output", the HashMap
contains {"output_base" => "/data/output"}.

But the OUTPUT_BASE override stored the FULL formatted string as the
value: {"output_base" => "output_base: /data/output"}. When TryFrom
later converts this to a PathBuf via `.map(Into::into)`, it produces
PathBuf("output_base: /data/output") — an invalid path.

This means the OUTPUT_BASE env var has never worked correctly. Fix by
storing the raw path string without the prefix.

Author: georgesfarah

crate_universe/src/cli/vendor.rs

@@ -183,7 +183,7 @@ impl BazelInfo {
         // Allow a predefined environment variable to take precedent. This
         // solves for the specific needs of Bazel CI on Github.
         if let Ok(path) = env::var("OUTPUT_BASE") {
-            bazel_info.insert("output_base".to_owned(), format!("output_base: {}", path));
+            bazel_info.insert("output_base".to_owned(), path);
         };
 
         BazelInfo::try_from(bazel_info)