Bump docs test suite timeout to 40min

The docs test suite is still timing out on CI at 35 minutes, so
pushing it to 40 minutes while we determine the cause of the slowdown.

Relates: elastic#49753
Backport of: elastic#51200

docs/src/test/java/org/elasticsearch/smoketest/DocsClientYamlTestSuiteIT.java

@@ -58,8 +58,8 @@
 import static org.elasticsearch.common.xcontent.ConstructingObjectParser.constructorArg;
 
 //The default 20 minutes timeout isn't always enough, please do not increase further than 30 before analyzing what makes this suite so slow
-// gh#49753 increasing timeout to 35 minutes until this gets fixes properly
-@TimeoutSuite(millis = 35 * TimeUnits.MINUTE)
+// gh#49753, tv#49753 : increasing timeout to 40 minutes until this gets fixes properly
+@TimeoutSuite(millis = 40 * TimeUnits.MINUTE)
 public class DocsClientYamlTestSuiteIT extends ESClientYamlSuiteTestCase {
 
     public DocsClientYamlTestSuiteIT(@Name("yaml") ClientYamlTestCandidate testCandidate) {