build: Preserve newlines when gathering stdout

If the chunk happens to end in a new line or other meaningful
whitespace, stripping it can lead to two words (e.g. targets)
being squished together and broken.

(cherry picked from commit c48a2da)

scripts/build-schema.mts

@@ -38,7 +38,7 @@ function _exec(cmd: string, captureStdout: boolean): Promise<string> {
     proc.stdout.on('data', (data) => {
       console.info(data.toString().trim());
       if (captureStdout) {
-        output += data.toString().trim();
+        output += data.toString();
       }
     });
     proc.stderr.on('data', (data) => console.info(data.toString().trim()));