Remove final on @ParametersDelegate field

Compile-time constant inlining may interfere with JCommander's processing if a field is made final - @ParametersDelegate fields are particularly misleading.  Remove the one instance of that and add warning comments elsewhere.  See

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=136469351

java/google/registry/tools/BigqueryCommand.java

@@ -21,6 +21,7 @@ import google.registry.bigquery.BigqueryConnection;
 abstract class BigqueryCommand implements Command {
 
   /** Parameter delegate for encapsulating flags needed to set up the {@link BigqueryConnection}. */
+  // Do not make this final - compile-time constant inlining may interfere with JCommander.
   @ParametersDelegate
   private BigqueryParameters bigqueryParameters = new BigqueryParameters();