Update "clone" to "code" based on UI change

What does this MR do?

On the project overview page, the Clone button was renamed to Code. This MR updates the relevant pages to make the docs match the UI.

Here's my grep with the results I did not change, and why:

$ grep -riI "\*\*Clone" .

# Not GitLab UI
./development/database/database_migration_pipeline.md:- **Clone details** - A link to the `Postgres.ai` thin clone created for this
./development/database/database_lab.md:   1. Provide a **Clone ID**: Something that uniquely identifies your clone, such as `yourname-testing-gitlabissue`.
./development/database/database_lab.md:1. In the **Clone details** page of the Postgres.ai web interface, copy and run
./development/database/database_lab.md:1. In the **Clone details** page of the Postgres.ai web interface, copy and run the `psql` connection string.
./ci/ci_cd_for_external_repos/bitbucket_integration.md:      - For **Git repository URL**, use the URL from the **Clone this repository** panel in Bitbucket.

# I checked, and this button didn't change on the Snippets page
./user/snippets.md:- Select **Clone**, then copy the URL to clone with SSH or HTTPS.

# I corrected the main statement. "Clone HTTPS (GRC)" is something else.
./user/project/repository/mirror/push.md:1. Open your new repository, and then select **Code > Clone HTTPS** (not **Clone HTTPS (GRC)**).

# Wikis also didn't change
./user/project/wiki/index.md:locally, select **Clone repository** from the right-hand sidebar of any wiki page,

# Unchanged items are a child step that did not change
./gitlab-basics/start-using-git.md:1. On the right-hand side of the page, select **Code**, then copy the URL for **Clone with SSH**.
./gitlab-basics/start-using-git.md:1. On the right-hand side of the page, select **Code**, then copy the URL for **Clone with HTTPS**.
./tutorials/make_first_git_commit/index.md:1. On your project page, select **Code**. Copy the URL for **Clone with SSH**.
./tutorials/update_commit_messages/index.md:   - **Clone with HTTPS** if your GitLab account uses basic username and password authentication.
./tutorials/update_commit_messages/index.md:   - **Clone with SSH** if you use SSH to authenticate with GitLab.

# Phrasing, not UI element
./topics/git/get_started.md:To create a copy of a remote repository's files on your computer, you **clone** it.

Related issues

• Related to Project: Merge clone and download options into ... (!137256 - merged) where the change was introduced
• Related to ✂️ UX Paper Cuts 16.7 → Project page (#430244 - closed)
• Related to Fix the download-artifact instructions (!140147 - merged) which handles the rest of the docs changes

Author's checklist

• Optional. Consider taking the GitLab Technical Writing Fundamentals course.
• Follow the:
  • Documentation process.
  • Documentation guidelines.
  • Style Guide.
• If you're adding or changing the main heading of the page (H1), ensure that the product tier badge is added.
• If you are a GitLab team member, request a review based on:
  • The documentation page's metadata.
  • The associated Technical Writer.

If you are a GitLab team member and 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.

Reviewer's 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 you aren't sure which tech writer to ask, use roulette or ask in the #docs Slack channel.

• If the content requires it, ensure the information is reviewed by a subject matter expert.
• Technical writer review items:
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    • Any task steps should be written as a numbered list.
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