Increase REST-Test Client Timeout to 60s (#46455)

We are seeing requests take more than the default 30s
which leads to requests being retried and returning
unexpected failures like e.g. "index already exists"
because the initial requests that timed out, worked
out functionally anyway.
=> double the timeout to reduce the likelihood of
the failures described in #46091
=> As suggested in the issue, we should in a follow-up
turn off retrying all-together probably

test/framework/src/main/java/org/elasticsearch/test/rest/ESRestTestCase.java

@@ -78,6 +78,7 @@ import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 import java.util.Set;
 import java.util.TreeSet;
 import java.util.concurrent.TimeUnit;
@@ -837,11 +838,9 @@ public abstract class ESRestTestCase extends ESTestCase {
             }
             builder.setDefaultHeaders(defaultHeaders);
         }
-        final String socketTimeoutString = settings.get(CLIENT_SOCKET_TIMEOUT);
-        if (socketTimeoutString != null) {
-            final TimeValue socketTimeout = TimeValue.parseTimeValue(socketTimeoutString, CLIENT_SOCKET_TIMEOUT);
-            builder.setRequestConfigCallback(conf -> conf.setSocketTimeout(Math.toIntExact(socketTimeout.getMillis())));
-        }
+        final String socketTimeoutString = Objects.requireNonNullElse(settings.get(CLIENT_SOCKET_TIMEOUT), "60s");
+        final TimeValue socketTimeout = TimeValue.parseTimeValue(socketTimeoutString, CLIENT_SOCKET_TIMEOUT);
+        builder.setRequestConfigCallback(conf -> conf.setSocketTimeout(Math.toIntExact(socketTimeout.getMillis())));
         if (settings.hasValue(CLIENT_PATH_PREFIX)) {
             builder.setPathPrefix(settings.get(CLIENT_PATH_PREFIX));
         }