Hide 'Embed' button for public snippets but in a non-public project or project's snippets visibility is `Only Project Members`
### Summary
Snippets of private/internal projects or projects with **Snippets visibility** set to **Only Project Members** are not embeddable; however, the UI still shows the **Embed** button.
### Steps to reproduce
1. Create a public snippet inside a private project
2. On the snippet page, you will see the **Embed** button. In the end, you won't be able to embed it (404)
### What is the current *bug* behavior?
The **Embed** button is shown even though the snippet is not embeddable
### What is the expected *correct* behavior?
The **Embed** button in the snippet page should be hidden for projects where snippets are not viewable
### Relevant logs and/or screenshots
**Public Snippet in Private Project:**
**Visiting the javascript file (used for embedding):**
### Output of checks
This bug happens on GitLab.com
#### Results of GitLab environment info
### Possible fixes
Improve checks for `embeddable()` in https://gitlab.com/gitlab-org/gitlab/-/blob/a8ea55db8badde24e8e0e019c65f0320f5b103fd/app/assets/javascripts/snippets/components/show.vue
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