Fix environments tab is empty after upgrading to 16.1

What does this MR do and why?

This MR fixes that on-premises users on GitLab 16.1 can't view anything in Environment page.

It seems that the Content Security Policy connect-src is set even if the Settings.gitlab.content_security_policy is disabled. (Here is an issue to enable it by default on all on-premises instances. It's not done yet)

This means only one connect-src: <kas-url> is set to the request headers. So essentially users are blocked to execute all requests except the <kas-url>. This is the reason why accessing to environments.json was blocked. Reference. We must set connect-src: self at first and append the connect-src: <kas-url> later.

This MR fixes it by skipping the connect-src: <kas-url> setting when the CSP is disabled on the instance.

Screenshots or screen recordings

This can be reproduced on gitlab review app. Accessing to Project > Operate > Environment page:

Before	After

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