test: disable unstable test case of rspack-cli (#8086)

packages/rspack-cli/tests/build/issue-6359/index.test.ts

@@ -8,7 +8,8 @@ it("should not have `process.env.WEBPACK_SERVE` set on build mode", async () =>
 	expect(mainJs).toContain("WEBPACK_SERVE=<EMPTY>");
 });
 
-it("should have `process.env.WEBPACK_SERVE` set on serve mode", async () => {
+// TODO: this test is not stable on CI, need to fix it
+it.skip("should have `process.env.WEBPACK_SERVE` set on serve mode", async () => {
 	await runWatch(__dirname, ["serve"], { killString: /rspack compiled/i });
 	// wait 1s to make sure the assets have been generated
 	await new Promise(resolve => setTimeout(resolve, 1000));