Downgrade rapids to 2602 for now. (#82)

Author: trivialfis

containers/ci_container.yml

@@ -4,7 +4,7 @@
 # containers/dockerfile/Dockerfile.CONTAINER_DEF
 
 x-rapids_versions:
-  stable: &rapids_version "26.04"
+  stable: &rapids_version "26.02"
 
 x-cuda_versions:
   cuda: &cuda_version "12.9.0"