fix(discovery): allow requireUpdate util to timeout in discovery/file/file_test.go.

The loop ran indefinitely if the condition isn't met.

Before, each iteration created a new timer channel which was always outpaced by
the other timer channel with smaller duration.

minor detail: There was a memory leak: resources of the ~10 previous timers were
constantly kept. With the fix, we may keep the resources of one timer around for defaultWait
but this isn't worth the changes to make it right.

Signed-off-by: machine424 <ayoubmrini424@gmail.com>

discovery/file/file_test.go

@@ -193,9 +193,10 @@ func (t *testRunner) targets() []*targetgroup.Group {
 func (t *testRunner) requireUpdate(ref time.Time, expected []*targetgroup.Group) {
 	t.Helper()
 
+	timeout := time.After(defaultWait)
 	for {
 		select {
-		case <-time.After(defaultWait):
+		case <-timeout:
 			t.Fatalf("Expected update but got none")
 			return
 		case <-time.After(defaultWait / 10):