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

Make HTTPInstaller.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/http_installer.go

@@ -152,7 +152,7 @@ func (i HTTPInstaller) Path() string {
 	if i.Source == "" {
 		return ""
 	}
-	return helmpath.DataPath("plugins", i.PluginName)
+	return filepath.Join(i.pluginsDir(), i.PluginName)
 }
 
 // SupportsVerification returns true if the HTTP installer can verify plugins