fix(plugin): use HELM_PLUGINS dir for local plugin installs

Make LocalInstaller.Path() use the first HELM_PLUGINS directory, matching base.Path() and OCI.

Signed-off-by: Yuhui Luo <92632263+lyh7c00@users.noreply.github.com>

internal/plugin/installer/local_installer.go

@@ -176,7 +176,7 @@ func (i *LocalInstaller) Path() string {
 		pluginName = stripPluginName(pluginName)
 	}
 
-	return helmpath.DataPath("plugins", pluginName)
+	return filepath.Join(i.pluginsDir(), pluginName)
 }
 
 // SupportsVerification returns true if the local installer can verify plugins