Go: Fix flaky TestScriptKillWithRoute race condition (#5950)

* Fix flaky TestScriptKillWithRoute by increasing timeout and replacing sleep with polling

The test was flaky because:
1. The script invoked in a goroutine hadn't started executing on the server
   before SCRIPT KILL was attempted, causing 'NotBusy' errors.
2. The 5-second timeout was insufficient for slow CI environments.
3. The fixed time.Sleep(1s) at the end was unreliable for confirming
   the script was no longer running.

Changes:
- Increase script duration from 6s to 10s to ensure it's still running
  when the kill succeeds.
- Increase kill polling timeout from 5s to 8s to accommodate slow
  script startup in CI.
- Replace time.Sleep(1s) at the end with a polling loop that waits
  for the 'notbusy' state, making the test deterministic.

Signed-off-by: Thomas Zhou <thomas.zhou@improving.com>
Signed-off-by: Thomas Zhou <thomaszhou64@gmail.com>

* Fix flaky TestScriptKillWithRoute by blocking on script execution

Restructure the test to match the working testFunctionKillNoWrite pattern:
- Run InvokeScriptWithRoute in the main thread (blocking) to guarantee
  the script is executing on the server before kill is attempted
- Run ScriptKill polling in a goroutine
- Use a longer request timeout (12s) so the invoke call blocks until killed

This eliminates the race condition where ScriptKill was called before
the script started, causing 'NotBusy' errors.

Verified: 250/250 sequential runs with 0 failures.

Fixes #5576

Signed-off-by: Thomas Zhou <thomaszhou64@gmail.com>

---------

Signed-off-by: Thomas Zhou <thomas.zhou@improving.com>
Signed-off-by: Thomas Zhou <thomaszhou64@gmail.com>

Author: xShinnRyuu

go/integTest/cluster_commands_test.go

@@ -2616,10 +2616,13 @@ func (suite *GlideTestSuite) TestScriptKillWithoutRoute() {
 }
 
 func (suite *GlideTestSuite) TestScriptKillWithRoute() {
-	invokeClient, err := suite.clusterClient(suite.defaultClusterClientConfig())
-	require.NoError(suite.T(), err)
 	killClient := suite.defaultClusterClient()
 
+	// Use a longer request timeout so InvokeScript blocks until killed
+	invokeConfig := suite.defaultClusterClientConfig().WithRequestTimeout(12 * time.Second)
+	invokeClient, err := suite.clusterClient(invokeConfig)
+	require.NoError(suite.T(), err)
+
 	// key for routing to a primary node
 	randomKey := uuid.NewString()
 	route := options.RouteOption{
@@ -2632,42 +2635,39 @@ func (suite *GlideTestSuite) TestScriptKillWithRoute() {
 	assert.True(suite.T(), strings.Contains(strings.ToLower(err.Error()), "notbusy"))
 
 	// Kill Running Code
-	code := CreateLongRunningLuaScript(6, true)
+	code := CreateLongRunningLuaScript(10, true)
 	script := options.NewScript(code)
 
-	go invokeClient.InvokeScriptWithRoute(context.Background(), *script, route)
-
-	timeout := time.After(5 * time.Second)
-	ticker := time.NewTicker(100 * time.Millisecond)
-	defer ticker.Stop()
-
+	// Kill in a goroutine - polls until the script is running, matching testFunctionKillNoWrite pattern
+	var killErr error
 	var result string
-	killed := false
-
-	for !killed {
-		select {
-		case <-timeout:
-			suite.T().Fatal("Timeout: SCRIPT KILL failed to execute in 5 seconds")
-		case <-ticker.C:
-			result, err = killClient.ScriptKillWithRoute(context.Background(), route)
-			if err == nil {
-				killed = true
-				continue
-			}
+	go func() {
+		timeout := time.After(8 * time.Second)
+		ticker := time.NewTicker(500 * time.Millisecond)
+		defer ticker.Stop()
 
-			if !strings.Contains(strings.ToLower(err.Error()), "notbusy") {
-				assert.NoError(suite.T(), err)
-				killed = true
+		for {
+			select {
+			case <-timeout:
+				return
+			case <-ticker.C:
+				result, killErr = killClient.ScriptKillWithRoute(context.Background(), route)
+				if killErr == nil {
+					return
+				}
 			}
 		}
-	}
+	}()
 
-	assert.NoError(suite.T(), err)
+	// Block until script is killed (returns error) - guarantees script is running on server
+	_, err = invokeClient.InvokeScriptWithRoute(context.Background(), *script, route)
+	assert.Error(suite.T(), err)
+	assert.True(suite.T(), strings.Contains(strings.ToLower(err.Error()), "script killed"))
+
+	assert.NoError(suite.T(), killErr)
 	assert.Equal(suite.T(), "OK", result)
 	script.Close()
 
-	time.Sleep(1 * time.Second)
-
 	// Ensure no script is running at the end
 	_, err = killClient.ScriptKillWithRoute(context.Background(), route)
 	assert.Error(suite.T(), err)