chore: Deactivate release freeze (#25307)

Co-authored-by: Yoshi Automation Bot <yoshi-automation@google.com>

Author: yoshi-code-bot

.kokoro/release-generated.sh

@@ -1,7 +1,7 @@
 #!/bin/bash
 
 # Set this to a nonempty string to freeze releases.
-FREEZE_RELEASES=true
+FREEZE_RELEASES=
 
 set -eo pipefail