Always check for root disks unless MINIO_CI_CD is set (#14232)

The current code considers a pool with all root disks to be as part
of a testing environment even if there are other pools with mounted
disks. This will result to illegitimate writing in root disks.

Fix this by simplifing the logic: require MINIO_CI_CD in order to skip
root disk check.

buildscripts/unaligned-healing.sh

@@ -30,6 +30,7 @@ function start_minio_16drive() {
     export MC_HOST_minio="http://minio:minio123@127.0.0.1:${start_port}/"
     unset MINIO_KMS_AUTO_ENCRYPTION # do not auto-encrypt objects
     export _MINIO_SHARD_DISKTIME_DELTA="5s" # do not change this as its needed for tests
+    export MINIO_CI_CD=1
 
     MC_BUILD_DIR="mc-$RANDOM"
     if ! git clone --quiet https://github.com/minio/mc "$MC_BUILD_DIR"; then