Merge pull request #67139 from NetApp/dev-random-fix-67091

Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions here: https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md.

Fix an issue about generation of secret key with invalid key size in gce

Replace /dev/random to /dev/urandom to avoid generation of secret key with invalid key size.



**What this PR does / why we need it**:
In GCE env, AESGCM encryption of secrets by default generates a secret key with /dev/random which sometime generates a key with invalid size.
This cause the cluster/kube-up.sh to fail in gce environment.

This PR replaces /dev/random with  /dev/urandom to have a secret key generated consistently with right size.

**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes #67091

**Special notes for your reviewer**:

**Release note**:

```release-note
cluster/gce: generate consistent key sizes in config-default.sh using /dev/urandom instead of /dev/random  
```

cluster/gce/config-default.sh

@@ -222,7 +222,7 @@ resources:
     - aesgcm:
         keys:
         - name: key1
-          secret: $(dd if=/dev/random bs=32 count=1 2>/dev/null | base64 | tr -d '\r\n')
+          secret: $(dd if=/dev/urandom iflag=fullblock bs=32 count=1 2>/dev/null | base64 | tr -d '\r\n')
 EOM
 )
 fi