Draft: Migrate "placement" values to match floating-ui placements

What does this MR do and why?

This change updates deprecated values of gitlab-ui prop values to match up to date floating-ui placements.

Pattern used:

Using VS Code:

• Search: (<gl-disclosure-dropdown[\s\S\r]*?icon="ellipsis_v"[\s\S\r]*)(placement="right")([\s\S\r]*?>)
• Replacment: $1placement="bottom-end"$3
• yarn lint:prettier:staged:fix

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

NA

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.