CI: fix the AlreadyExists error during snapshot installation

In the recent CI, an error occasionally pops up saying
serviceaccounts snapshot-controller already exists.
not sure if the public CI has some caching mechanism.
Using kubectl apply instead of create solves this problem

Signed-off-by: Xin Yang <[email protected]>
Change-Id: I952fcf1df46a953ba67f4922a2ec12cf510c06c4
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk-csi/+/20432
Reviewed-by: Yibo Cai <[email protected]>
Tested-by: SPDK CI Jenkins <[email protected]>
Reviewed-by: Jim Harris <[email protected]>

scripts/install-snapshot.sh

@@ -22,7 +22,7 @@ function install_snapshot_controller() {
 		namespace="default"
 	fi
 
-	create_or_delete_resource "create" ${namespace}
+	create_or_delete_resource "apply" ${namespace}
 
 	pod_ready=false
 	INC=0