Allow configure timeout in REST tests from sys props (elastic#133748)

When debugging REST tests with a remote debugger, we often need to 
manually increase the client socket timeout in the code. This allows us
to spend more time in the debugger without the query failing due to a
timeout.

This change allows configuring the client socket timeout from a system 
property.

For example:

``` 
./gradlew :x-pack:plugin:esql:qa:server:single-node:yamlRestTest
--tests "org.elasticsearch.xpack.esql.qa.single_node.EsqlClientYamlIT"
-Dtests.client.socket.timeout=10m 

```

Author: dnhatn

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

@@ -1609,6 +1609,9 @@ protected Settings restClientSettings() {
             final var projectId = System.getProperty("tests.rest.project.id");
             builder.put(ThreadContext.PREFIX + ".X-Elastic-Project-Id", projectId);
         }
+        if (System.getProperty("tests." + CLIENT_SOCKET_TIMEOUT) != null) {
+            builder.put(CLIENT_SOCKET_TIMEOUT, System.getProperty("tests." + CLIENT_SOCKET_TIMEOUT));
+        }
         return builder.build();
     }