Remove all no-import-assign errors from tests

[DarioR01]

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Following the meeting about upgrading major dependencies, we discussed the no-import-assign rule coming from eslint-config-airbnb to v19.
This anti-pattern of importing something into a namespace and assigning that namespace a different value is not recommended.

We only use this anti-pattern in our unit test cases, this PR will take care of places where we use this pattern so that we can later enforce this by upgrading to the new major version of eslint-config-airbnb.

Describe the solution you'd like

1. Identify a solution that will allow our unit tests to not use the above-described anti-pattern.
2. Identify all the files that use the anti-pattern described above (marked with no-import-assign error).
3. Apply the found solution to all the identified files.

To identify the files

1. checkout into renovate/eslint-config-airbnb-19.x with git checkout renovate/eslint-config-airbnb-19.x
2. run yarn && yarn test:lint
3. Locate all files with no-import-assign error description on the output

Alternatively

1. Go to https://github.com/bbc/simorgh/runs/5754191013?check_suite_focus=true
2. Locate all files with no-import-assign error description

Alternatively

1. checkout into renovate/eslint-config-airbnb-19.x with git checkout renovate/eslint-config-airbnb-19.x
2. run yarn && yarn test:lint
3. Locate all files with no-import-assign error description on the output

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Testing notes
[Tester to complete]

Dev insight: Will Cypress tests be required or are unit tests sufficient? Will there be any potential regression? etc

• This feature is expected to need manual testing.

Checklist

• (BBC contributors only) This issue follows the repository use guidelines

Additional context
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