Get-and-set accounts, since other updates may have made them stale.

Co-authored-by: Chris Eager <79161849+eager-signal@users.noreply.github.com>

service/src/main/java/org/whispersystems/textsecuregcm/storage/ContactDiscoveryWriter.java

@@ -27,7 +27,7 @@ public class ContactDiscoveryWriter extends AccountDatabaseCrawlerListener {
       throws AccountDatabaseCrawlerRestartException {
     for (Account account : chunkAccounts) {
       if (account.isCanonicallyDiscoverable() != account.shouldBeVisibleInDirectory()) {
-        accounts.update(account);
+        accounts.get(account.getUuid()).ifPresent(accounts::update);
       }
     }
   }