test(integration): allow to conitnue when test suite fails (#45682)

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Partially resolves WEB-544.

This PR adds a new detection to the external env variable
`NEXT_TEST_CONTINUE_ON_ERROR`. If those variable is set, even if a suite
of test fails test runner will keep executing remaining tests.

Turbopack (vercel/turbo) runs Next.js integration tests to track its
feature parity to the existing Next.js features and currently it is
expected to fail on certain test: however, we still want to execute all
of the tests to track how many tests are passing / fails.

Once this change lands turbopack need further verification to see if all
of tests are actually running.

## Bug

- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Errors have a helpful link attached, see
[`contributing.md`](https://github.com/vercel/next.js/blob/canary/contributing.md)

## Feature

- [ ] Implements an existing feature request or RFC. Make sure the
feature request has been accepted for implementation before opening a
PR.
- [ ] Related issues linked using `fixes #number`
- [ ]
[e2e](https://github.com/vercel/next.js/blob/canary/contributing/core/testing.md#writing-tests-for-nextjs)
tests added
- [ ] Documentation added
- [ ] Telemetry added. In case of a feature if it's used or not.
- [ ] Errors have a helpful link attached, see
[`contributing.md`](https://github.com/vercel/next.js/blob/canary/contributing.md)

## Documentation / Examples

- [ ] Make sure the linting passes by running `pnpm build && pnpm lint`
- [ ] The "examples guidelines" are followed from [our contributing
doc](https://github.com/vercel/next.js/blob/canary/contributing/examples/adding-examples.md)

run-tests.js

@@ -17,6 +17,7 @@ const DEFAULT_NUM_RETRIES = os.platform() === 'win32' ? 2 : 1
 const DEFAULT_CONCURRENCY = 2
 const RESULTS_EXT = `.results.json`
 const isTestJob = !!process.env.NEXT_TEST_JOB
+const shouldContinueTestsOnError = !!process.env.NEXT_TEST_CONTINUE_ON_ERROR
 const TIMINGS_API = `https://api.github.com/gists/4500dd89ae2f5d70d9aaceb191f528d1`
 const TIMINGS_API_HEADERS = {
   Accept: 'application/vnd.github.v3+json',
@@ -418,7 +419,14 @@ async function main() {
             console.log(`Failed to load test output`, err)
           }
         }
-        cleanUpAndExit(1)
+
+        if (!shouldContinueTestsOnError) {
+          cleanUpAndExit(1)
+        } else {
+          console.log(
+            `CONTINUE_ON_ERROR enabled, continuing tests after ${test} failed`
+          )
+        }
       }
       sema.release()
       dirSema.release()