change HTTP method to comply with spec (#9100)

There is discrepancy with the spec, it has PUT

storage_controller/src/http.rs

@@ -1849,7 +1849,7 @@ pub fn make_router(
                 RequestName("v1_tenant_timeline"),
             )
         })
-        .post(
+        .put(
             "/v1/tenant/:tenant_id/timeline/:timeline_id/archival_config",
             |r| {
                 tenant_service_handler(

storage_controller/src/pageserver_client.rs

@@ -238,7 +238,7 @@ impl PageserverClient {
     ) -> Result<()> {
         measured_request!(
             "timeline_archival_config",
-            crate::metrics::Method::Post,
+            crate::metrics::Method::Put,
             &self.node_id_label,
             self.inner
                 .timeline_archival_config(tenant_shard_id, timeline_id, req)