Do not generate a coverage report when visiting local HTML files with `expectBackendCoverageOnly` enabled

Problem:
When visiting a local HTML file (cypress/downloads/test.html), the coverage report is not generated. However, when visiting an external URL like https://docs.cypress.io/app/tooling/code-coverage, the coverage report is successfully generated.

and the error message is `code-coverage/test-apps/backend/.nyc_output/out.json has no coverage information
Did you forget to instrument your web application?`

Cypress Configuration:
```js
const { defineConfig } = require('cypress')

module.exports = defineConfig({
fixturesFolder: false,
env: {
codeCoverage: {
url: 'http://localhost:3003/__coverage__',
expectBackendCoverageOnly: true
},
},
e2e: {
setupNodeEvents(on, config) {
return require('./cypress/plugins/index.js')(on, config)
},
baseUrl: 'http://localhost:3003',
},
})
```

Test Spec:
```js
///

context('Converage Test', () => {
it('backend test', function() {
cy.visit('/')
cy.request('/hello')
})

it('visit local html file', {baseUrl: null}, () => {
cy.visit('cypress/downloads/test.html') // failed to generate coverage report
// cy.visit('https://docs.cypress.io/app/tooling/code-coverage') //Successfully generated the coverage report.
})
})
```