pdr: Stabilize pldm_entity_node_get_remote_container_id()

Use of pldm_entity_node_get_remote_container_id() is demonstrated here:

https://gerrit.openbmc.org/c/openbmc/pldm/+/39198

Change-Id: If8df1d73b1ea6e319b200ee76d4d4ac2e00ef9aa
Signed-off-by: Pavithra Barithaya <pavithra.b@ibm.com>
diff --git a/src/pdr.c b/src/pdr.c
index e78d8cd..72cab7e 100644
--- a/src/pdr.c
+++ b/src/pdr.c
@@ -460,7 +460,7 @@
 	return node->entity;
 }
 
-LIBPLDM_ABI_TESTING
+LIBPLDM_ABI_STABLE
 uint16_t
 pldm_entity_node_get_remote_container_id(const pldm_entity_node *entity)
 {