Fix Optimize settings form displays "use snippet instructions" flash.

[kuasha420]

Summary

Addresses issue #3720

Relevant technical choices

Checklist

• My code is tested and passes existing unit tests.
• My code has an appropriate set of unit tests which all pass.
• My code is backward-compatible with WordPress 4.7 and PHP 5.6.
• My code follows the WordPress coding standards.
• My code has proper inline documentation.
• I have added a QA Brief on the issue linked above.
• I have signed the Contributor License Agreement (see https://cla.developers.google.com/).

[github-actions]

Size Change: +3 B (0%)

Total Size: 1.14 MB

Filename	Size	Change
./dist/assets/js/googlesitekit-modules-optimize.********************.js	18.3 kB	+3 B (0%)

ℹ️ View Unchanged

Filename	Size
./dist/assets/css/admin.css	38.5 kB
./dist/assets/css/adminbar.css	8 kB
./dist/assets/css/wpdashboard.css	4.58 kB
./dist/assets/js/33.********************.js	3.12 kB
./dist/assets/js/analytics-advanced-tracking.js	769 B
./dist/assets/js/googlesitekit-activation.********************.js	37.9 kB
./dist/assets/js/googlesitekit-adminbar.********************.js	30.8 kB
./dist/assets/js/googlesitekit-api.********************.js	9.04 kB
./dist/assets/js/googlesitekit-base.********************.js	1.58 kB
./dist/assets/js/googlesitekit-dashboard-details.********************.js	44.4 kB
./dist/assets/js/googlesitekit-dashboard-splash.********************.js	52.1 kB
./dist/assets/js/googlesitekit-dashboard.********************.js	44.6 kB
./dist/assets/js/googlesitekit-data.********************.js	1.65 kB
./dist/assets/js/googlesitekit-datastore-forms.********************.js	8.73 kB
./dist/assets/js/googlesitekit-datastore-location.********************.js	2.03 kB
./dist/assets/js/googlesitekit-datastore-site.********************.js	13.2 kB
./dist/assets/js/googlesitekit-datastore-ui.********************.js	8.71 kB
./dist/assets/js/googlesitekit-datastore-user.********************.js	20.9 kB
./dist/assets/js/googlesitekit-i18n.js	3.92 kB
./dist/assets/js/googlesitekit-idea-hub-notice.********************.js	2.4 kB
./dist/assets/js/googlesitekit-idea-hub-post-list.********************.js	23.6 kB
./dist/assets/js/googlesitekit-module.********************.js	44.4 kB
./dist/assets/js/googlesitekit-modules-adsense.********************.js	44.9 kB
./dist/assets/js/googlesitekit-modules-analytics-4.********************.js	18.8 kB
./dist/assets/js/googlesitekit-modules-analytics.********************.js	66.3 kB
./dist/assets/js/googlesitekit-modules-idea-hub.********************.js	23.8 kB
./dist/assets/js/googlesitekit-modules-pagespeed-insights.********************.js	16.3 kB
./dist/assets/js/googlesitekit-modules-search-console.********************.js	28.4 kB
./dist/assets/js/googlesitekit-modules-subscribe-with-google.********************.js	16.4 kB
./dist/assets/js/googlesitekit-modules-tagmanager.********************.js	29.8 kB
./dist/assets/js/googlesitekit-modules.********************.js	16.4 kB
./dist/assets/js/googlesitekit-polyfills.********************.js	377 B
./dist/assets/js/googlesitekit-settings.********************.js	48.9 kB
./dist/assets/js/googlesitekit-user-input.********************.js	45.1 kB
./dist/assets/js/googlesitekit-vendor.********************.js	312 kB
./dist/assets/js/googlesitekit-widgets.********************.js	11.4 kB
./dist/assets/js/googlesitekit-wp-dashboard.********************.js	32.9 kB
./dist/assets/js/runtime.********************.js	1.19 kB

_{compressed-size-action}

[eugene-manuilov]

LGTM