Use different data stream name when simulating index template (#1949)

Use a different data stream name when simulating to check if synthetic is enabled.
There seems to be some conflict if the same name is reused. Maybe related to
elastic/elasticsearch#84256 or some similar issue.

Author: jsoriano

internal/testrunner/runners/system/testdata/elasticsearch-8-mock-synthetic-mode-couchdb.yaml

@@ -79,7 +79,7 @@ interactions:
                 - go-elasticsearch/7.17.10 (linux amd64; Go 1.22.1)
             X-Elastic-Client-Meta:
                 - es=7.17.10,go=1.22.1,t=7.17.10,hc=1.22.1
-        url: https://127.0.0.1:9200/_index_template/_simulate_index/metrics-couchdb.server-12345
+        url: https://127.0.0.1:9200/_index_template/_simulate_index/metrics-couchdb.server-12345simulated
         method: POST
       response:
         proto: HTTP/1.1

internal/testrunner/runners/system/testdata/elasticsearch-8-mock-synthetic-mode-dummy.yaml

@@ -79,7 +79,7 @@ interactions:
                 - go-elasticsearch/7.17.10 (linux amd64; Go 1.22.1)
             X-Elastic-Client-Meta:
                 - es=7.17.10,go=1.22.1,t=7.17.10,hc=1.22.1
-        url: https://127.0.0.1:9200/_index_template/_simulate_index/logs-logs_synthetic_mode.synthetic-12345
+        url: https://127.0.0.1:9200/_index_template/_simulate_index/logs-logs_synthetic_mode.synthetic-12345simulated
         method: POST
       response:
         proto: HTTP/1.1

internal/testrunner/runners/system/testdata/elasticsearch-8-mock-synthetic-mode-nginx-logsdb.yaml

@@ -79,7 +79,7 @@ interactions:
                 - go-elasticsearch/7.17.10 (linux amd64; Go 1.22.1)
             X-Elastic-Client-Meta:
                 - es=7.17.10,go=1.22.1,t=7.17.10,hc=1.22.1
-        url: https://127.0.0.1:9200/_index_template/_simulate_index/logs-nginx.access-12345
+        url: https://127.0.0.1:9200/_index_template/_simulate_index/logs-nginx.access-12345simulated
         method: POST
       response:
         proto: HTTP/1.1

internal/testrunner/runners/system/testdata/elasticsearch-8-mock-synthetic-mode-nginx.yaml

@@ -79,7 +79,7 @@ interactions:
                 - go-elasticsearch/7.17.10 (linux amd64; Go 1.22.1)
             X-Elastic-Client-Meta:
                 - es=7.17.10,go=1.22.1,t=7.17.10,hc=1.22.1
-        url: https://127.0.0.1:9200/_index_template/_simulate_index/logs-nginx.access-12345
+        url: https://127.0.0.1:9200/_index_template/_simulate_index/logs-nginx.access-12345simulated
         method: POST
       response:
         proto: HTTP/1.1

internal/testrunner/runners/system/tester.go

@@ -614,7 +614,9 @@ func (r *tester) runTestPerVariant(ctx context.Context, result *testrunner.Resul
 }
 
 func isSyntheticSourceModeEnabled(ctx context.Context, api *elasticsearch.API, dataStreamName string) (bool, error) {
-	resp, err := api.Indices.SimulateIndexTemplate(dataStreamName,
+	// We append a suffix so we don't use an existing resource, what may cause conflicts in old versions of
+	// Elasticsearch, such as https://github.com/elastic/elasticsearch/issues/84256.
+	resp, err := api.Indices.SimulateIndexTemplate(dataStreamName+"simulated",
 		api.Indices.SimulateIndexTemplate.WithContext(ctx),
 	)
 	if err != nil {