Remove manual yarn postpack invocation

Signed-off-by: Eric Peterson <ericpeterson@spotify.com>

.changeset/cli-postpack-schmostschmack.md

@@ -0,0 +1,5 @@
+---
+'@backstage/cli': patch
+---
+
+The `build-workspace` command no longer manually runs `yarn postpack`, relying instead on the fact that running `yarn pack` will automatically invoke the `postpack` script. No action is necessary if you are running the latest version of yarn 1, 3, or 4.

packages/cli/src/lib/packager/createDistWorkspace.ts

@@ -309,10 +309,6 @@ async function moveToDistWorkspace(
     await run('yarn', ['pack', '--filename', archivePath], {
       cwd: target.dir,
     });
-    // TODO(Rugvip): yarn pack doesn't call postpack, once the bug is fixed this can be removed
-    if (target.packageJson?.scripts?.postpack) {
-      await run('yarn', ['postpack'], { cwd: target.dir });
-    }
 
     const outputDir = relativePath(paths.targetRoot, target.dir);
     const absoluteOutputPath = resolvePath(workspaceDir, outputDir);