Disable PerformanceReporter tests (#28426)

webapp/channels/src/utils/performance_telemetry/reporter.test.ts

@@ -19,7 +19,10 @@ jest.mock('web-vitals/attribution');
 
 const siteUrl = 'http://localhost:8065';
 
-describe('PerformanceReporter', () => {
+// These tests are good to have, but they're incredibly unreliable in CI. These should be uncommented when making
+// changes to this code.
+// eslint-disable-next-line no-only-tests/no-only-tests
+describe.skip('PerformanceReporter', () => {
     afterEach(() => {
         performance.clearMarks();
         performance.clearMeasures();