Update free trial page redirect

Why is this change being made?

An update was made to the Free Trial page as part of this this issue that allows the use of a URL param to specify which tab is open (self managed vs saas).

This MR updates the redirects file to achieve the following:

• Update the comp_op value to allow for the new params to work (the current value still redirects everything to the root /free-trial/ page).
• /free-trial/self-managed, which currently routes to the default page state (SaaS tab open), should now load the page with the Self-Managed state.

Author Checklist

• Provided a concise title for this Merge Request (MR)
• Added a description to this MR explaining the reasons for the proposed change, per say why, not just what
  • Copy/paste the Slack conversation to document it for later, or upload screenshots. Verify that no confidential data is added.
• Assign reviewers for this MR to the correct Directly Responsible Individual/s (DRI)
  • If the DRI for the page/s being updated isn’t immediately clear, then assign it to one of the people listed in the Maintained by section on the page being edited
  • If your manager does not have merge rights, please ask someone to merge it AFTER it has been approved by your manager in #mr-buddies
• If the changes affect team members, or warrant an announcement in another way, please consider posting an update in #whats-happening-at-gitlab linking to this MR
  • If this is a change that directly impacts the majority of global team members, it should be a candidate for #company-fyi. Please work with internal communications and check the handbook for examples.

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