feat(drawer): update when not to use popover docs

What does this MR do?

This MR adds a bullet point to "when not to use" popover docs to clarify when a drawer would be preferred. This MR originates from this issue thread.

Does this MR meet the acceptance criteria?

• The MR title and commit messages meet the Pajamas commit conventions.
• [ x The “What does this MR do?” section in the MR description is filled out, explaining the reasons for and scope of the proposed changes, per “Say why not just what”.
  • For example, if the MR is focused on usage guidelines, addressing accessibility challenges could be added in a separate MR.
• Relevant label(s) are applied to the MR.
• The MR is added to a milestone.
• [-] If creating a new component page from scratch, it follows the page template structure.
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• Review requested from any GitLab designer or directly from a maintainer or trainee maintainer.

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