Docs: Clarify where and how you can use SAST pre-compilation

What does this MR do?

1. Add a specific statement that the SAST pre-compilation strategy only works for analyzers that support the COMPILE=false option.
2. While editing this section, attempt to provide some explanatory background and clarify the content. I found that I didn't really understand some of the existing language.

This change ended up being bigger than I expected it to be initially. I'm open to splitting out the new content (1) from the other stuff (2).

Related issues

This issue doesn't arise from a specific GitLab issue. However, I became aware of this issue because of a Support interaction in ZD #232019, wherein one attempted issue resolution was to enable pre-compilation for .NET. However, we don't support pre-compilation for .NET. I then reviewed the documentation and realized it was easy to miss the cases in which pre-compilation would work or not work.

Following this, I asked in Slack and there was a brief conversation about the answer.

Author's checklist

• Consider taking the GitLab Technical Writing Fundamentals course.
  • Might do this eventually, but I have the MR ready :)
• Follow the:
  • Documentation process.
  • Documentation guidelines.
  • Style Guide.
  • I believe I did, but please call me out if I misunderstood anything!
• N/A Ensure that the product tier badge is added to topic's h1.
• Request a review based on:
  • The documentation page's metadata.
  • The associated Technical Writer.

If you are only adding documentation, do not add any of the following labels:

• ~"frontend"
• ~"backend"
• ~"type::bug"
• ~"database"

These labels cause the MR to be added to code verification QA issues.

Review checklist

Documentation-related MRs should be reviewed by a Technical Writer for a non-blocking review, based on Documentation Guidelines and the Style Guide.

• If the content requires it, ensure the information is reviewed by a subject matter expert.
• Technical writer review items:
  • Ensure docs metadata is present and up-to-date.
  • Ensure the appropriate labels are added to this MR.
  • If relevant to this MR, ensure content topic type principles are in use, including:
    • The headings should be something you'd do a Google search for. Instead of Default behavior, say something like Default behavior when you close an issue.
    • The headings (other than the page title) should be active. Instead of Configuring GDK, say something like Configure GDK.
    • Any task steps should be written as a numbered list.
    • If the content still needs to be edited for topic types, you can create a follow-up issue with the docs-technical-debt label.
• Review by assigned maintainer, who can always request/require the reviews above. Maintainer's review can occur before or after a technical writer review.
• Ensure a release milestone is set.