Add crash canary environment for proxy

This makes it possible to set up canary testing on crash.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=240210405

java/google/registry/proxy/ProxyConfig.java

@@ -28,8 +28,9 @@ public class ProxyConfig {
     PRODUCTION_CANARY,
     SANDBOX,
     SANDBOX_CANARY,
-    ALPHA,
     CRASH,
+    CRASH_CANARY,
+    ALPHA,
     LOCAL,
   }