revised the channel addition, logic untouched

[arash-e-at-moz]

Relevant Links

Bugzilla: N/A
TestRail: N/A

Description of Code / Doc Changes

Revised choose_test_channel.py when adding channels based on committed files. Logic stays the same.

Process Changes Required

Mark the relevant boxes:

• Adds a dependency (rerun pipenv install)
• Changes the BasePage
• Changes or creates a BOM/POM (name the object model): _
• Changes CI flow
• Changes scheduled Beta or DevEdition
• Changes Git hooks or Github settings
• Changes L10n harness

Screenshots or Explanations

N/A

Comments or Future Work

N/A

Workflow Checklist

• Please request reviewers
• If this is an unblocker, please post in Slack.
• If asked to address comments, please resolve conversations.
• If asked to change code, please re-request review from the person who wanted changes.

Thank you!

[ben-c-at-moz]

Minor thing, but it's not blocking. LGTM