Rebases page: 2nd round of CTRT revisions

What does this MR do?

As part of technical-writing#702 (closed), runs a second pass against https://docs.gitlab.com/ee/topics/git/git_rebase.html to bring it closer to GitLab tone and style. Does not complete the work, but continues to bring us closer.

Notable changes:

• Shifts from force-push to force push. I really prefer the former, but I can't find evidence that the Git documentation writes it that way, so back to the awkward-looking force push it is.
• Moves ### Before rebasing up and changes it to a H2 (Back up a branch before rebase) to bring it closer to task format.
• Shifts ## Git rebase down the page and changes it to ## Rebase a branch to follow task format.
• With ## Rebase a branch closer, rename and improve the nesting for the sub-subheads:
  • Regular rebase (I left the name alone because I hesitated - we could say From the command line but interactive rebases are also in the CLI...), remains H3
  • Rebase from the GitLab UI becomes From the GitLab UI and shifts from H4 to H3
• Cuts one-sentence anecdote links and shifts them to a new Related topics H2 at the bottom of the page
• Reshapes the language in subheads Back up a branch before rebase, Rebase a branch, and Regular rebase to be more active
• Changes code blocks to inline code in Back up a branch before rebase, Rebase a branch, and Regular rebase to make the examples shorter, less intimidating, and easier to scan

Related issues

Related to FY23Q4 TW OKR: Refactor high visibility pages f... (technical-writing#702 - closed)

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:
  • Ensure docs metadata is present and up-to-date.
  • Ensure the appropriate labels are added to this MR.
  • Ensure a release milestone is set.
  • 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.