Improve tests on Basic JS array challenges

[dhcodes]

Pre-Submission Checklist

• Your pull request targets the staging branch of FreeCodeCamp.
• Branch starts with either fix/, feature/, or translate/ (e.g. fix/signin-issue)
• You have only one commit (if not, squash them into one commit).
• All new and existing tests pass the command npm run test-challenges. Use git commit --amend to amend any fixes.

Type of Change

• Small bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds new functionality)
• Breaking change (fix or feature that would change existing functionality)
• Add new translation (feature adding new translations)

Checklist:

• Tested changes locally.
• Closes currently open issue (replace XXXX with an issue no): Closes Case check not done for the result #9806

Description

Per the issue #9806 I removed the .toLowerCase() from the unshift() challenge and made all array challenges use strict equality with doing number comparisons to prevent strings from passing as numbers. I tested these 4 challenges locally and the tests appear to be valid.

[BKinahan]

Travis is taking his sweet time, but I tested locally and each challenge runs as expected.

LGTM 👍

[dhcodes]

Even Travis deserves a coffee break @BKinahan

[ghost]

LGTM 👍

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