Bump docs test suite timeout to 40min (elastic#51205)

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) {