Remove use of 'shallow' (react-unit-test-utils) in following components/files:

• src/editors/sharedComponents/ImageUploadModal/ImageSettingsModal/index.test.jsx
• src/editors/sharedComponents/CodeEditor/index.test.jsx
• src/editors/sharedComponents/ErrorBoundary/ErrorPage.test.jsx
• src/editors/containers/VideoEditor/components/VideoSettingsModal/components/HandoutWidget/index.test.jsx
• src/editors/sharedComponents/ExpandableTextArea/index.test.jsx