chore: improve cypress runs on forks (#4924)

cypress/run.js

@@ -0,0 +1,41 @@
+const execa = require('execa');
+const globby = require('globby');
+
+const runCypress = async () => {
+  if (process.env.IS_FORK === 'true') {
+    const machineIndex = parseInt(process.env.MACHINE_INDEX);
+    const machineCount = parseInt(process.env.MACHINE_COUNT);
+    const specs = await globby(['cypress/integration/*spec*.js']);
+    const specsPerMachine = Math.floor(specs.length / machineCount);
+    const start = (machineIndex - 1) * specsPerMachine;
+    const machineSpecs =
+      machineIndex === machineCount
+        ? specs.slice(start)
+        : specs.slice(start, start + specsPerMachine);
+
+    await execa(
+      'cypress',
+      ['run', '--browser', 'chrome', '--headless', '--spec', machineSpecs.join(',')],
+      { stdio: 'inherit', preferLocal: true },
+    );
+  } else {
+    await execa(
+      'cypress',
+      [
+        'run',
+        '--browser',
+        'chrome',
+        '--headless',
+        '--record',
+        '--parallel',
+        '--ci-build-id',
+        process.env.GITHUB_SHA,
+        '--group',
+        'GitHub CI',
+      ],
+      { stdio: 'inherit', preferLocal: true },
+    );
+  }
+};
+
+runCypress().catch(error => console.error(error));