Remove Construct quickstart pages

[guolau]

Affected Components

• Content & Marketing
• Pricing
• Test
• Docs
• Learn
• Other

Summary of changes

• Remove Construct quickstart pages (Browser Check, Playwright Check)
• Small note about how Constructs require the Checkly CLI. (The Constructs and CLI are separate sections, so we should be very clear that Constructs require the CLI.)

Rationale

I think the execution is lacking enough that we should remove these two pages.

• Main issue: this looks to be AI-generated and unverified. It looks correct at a glance, but I'm not sure if anyone has actually tested it. For the sake of time, I default to removing this kind of content.
• The Playwright Check quickstart is mostly redundant, as we have a very similar quickstart in the main Docs section

I like the idea of quickstart guides. IMO we should consider re-adding similar guides that are more detailed.

Source: https://linear.app/checklyhq/issue/DOC-44/quickstart-guide-link-for-browser-checks-is-broken