Define TestRule that manages cache use in tests

All current tests that use caches with custom data expiry values
now restore the default config when teardown. We need to prevent
new unsafe uses from being introduced.

Restoration code have also been added to a few other tests that modifies
static fields.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=228888041

java/google/registry/tools/server/RefreshDnsForAllDomainsAction.java

@@ -79,9 +79,7 @@ public class RefreshDnsForAllDomainsAction implements Runnable {
 
     private static final long serialVersionUID = 1455544013508953083L;
 
-    @NonFinalForTesting
-    @VisibleForTesting
-    static DnsQueue dnsQueue = DnsQueue.create();
+    @NonFinalForTesting private static DnsQueue dnsQueue = DnsQueue.create();
 
     private final ImmutableSet<String> tlds;
 
@@ -109,5 +107,12 @@ public class RefreshDnsForAllDomainsAction implements Runnable {
         getContext().incrementCounter("domains on non-targeted TLDs skipped");
       }
     }
+
+    @VisibleForTesting
+    public static DnsQueue setDnsQueueForTest(DnsQueue testQueue) {
+      DnsQueue currentQueue = dnsQueue;
+      dnsQueue = testQueue;
+      return currentQueue;
+    }
   }
 }