Hide CSAT by default

[Vinnl]

This PR fixes #1564.

Only display the CSAT if the script to handle its interactions was
properly loaded (i.e. not blocked by an adblocker).

How to test: Make sure your browser language is set to en-US, is in the US, you don't have RECRUITMENT_BANNER_* env vars set, and you're logged in to an account that has had Premium for at least seven days. (Alternatively, add or True to line 21 of header.html.) You should see the CSAT banner.

Now install/enable an adblocker. You should no longer see the banner. (Whereas before, it would be visible but just not work.)

• l10n dependencies have been merged, if any.
• I've added a unit test to test for potential regressions of this bug (or this is a front-end change, where we don't yet have unit test infrastructure).
• I've added or updated relevant docs in the docs/ directory.
• All UI revisions follow the coding standards, and use Protocol tokens where applicable (see /static/scss/libs/protocol/css/includes/tokens/dist/index.scss).
• Commits in this PR are minimal and have descriptive commit messages.

[maxxcrawford]

Approving with a known merge conflict incoming.

If you need to land this before #1545, please add that pesky ?.

[maxxcrawford]

Issue: I ran into a bug while testing another PR and added a fix in this commit: 98157cb

Suggestion: We will need to port this over/resolve a merge conflict at some point soon.

Suggested change

	csatWrapperEl.classList.add("is-visible");
	csatWrapperEl?.classList.add("is-visible");

[Vinnl]

That merge conflict should be fairly easy to resolve, no? 5de9430

[pendantry]

Um. I'm not entirely sure how this GitHub thing works, apologies if I'm being premature with this feedback:

Has the issue of this non-working banner been fixed, or is there more to do?

Because I'm still seeing it (it still doesn't work):

Notes:

1. I'm not in the US, I'm in the UK. I don't have English (US) set, I have English (GB) set (because I'm English; go figure).
2. I've logged out of Firefox Relay, and logged back in again (just in case that might be relevant).
3. The banner disappears if I disable AdBlockerUltimate:

... and it appears if I enable it:

Reversed logic somewhere? Or simply a continuation of the grudge against the British Empire (as was)? ;)

[Vinnl]

Sorry @pendantry, the fix has been accepted into the main codebase, but it hasn't been published to the main website yet. I believe that when we publish to the main website, that is announced here, but in any case it should land soon-ish.