Add active clusters config to domain schema

[taylanisikdemir]

What changed?

• Added active cluster config to domain replication config type in Cassandra. It's a blob column which corresponds to types.ActiveClusters serialized. SQL stores already serialize the whole domain info so no schema change there.
• Updated domain handlers for active-active domains. More e2e testing on this will be added later.

Detailed Description
[In-depth description of the changes made to the schema or interfaces, specifying new fields, removed fields, or modified data structures]

CREATE TYPE domain_replication_config (
  active_cluster_name text,
  clusters            list<frozen<cluster_replication_config>>,
  active_clusters_config blob,                       -- new field
  active_clusters_config_encoding text,      -- new field
);

Impact Analysis

• Backward Compatibility: [Analysis of backward compatibility]
  It's not backward compatible so we are not going to start populating this field until DB schema is upgraded and no rollbacks anticipated.
• Forward Compatibility: [Analysis of forward compatibility]

Testing Plan

• Unit Tests: [Do we have unit test covering the change?]
  Added/updated relevant unit tests to cover the new fields as well as absence of new fields.

Added extra test cases to UpdateDomain handler for active-active cases.

• Persistence Tests: [If the change is related to a data type which is persisted, do we have persistence tests covering the change?]
  No changes
• Integration Tests: [Do we have integration test covering the change?]
  No changes
• Compatibility Tests: [Have we done tests to test the backward and forward compatibility?]
  Not needed.

Rollout Plan

• What is the rollout plan?
  Land the change, create prerelease and run schema upgrade tool before deploying the new version

• Does the order of deployment matter?
  As usual, first apply DB schema change then deploy binary.

• Is it safe to rollback? Does the order of rollback matter?
  It's safe to rollback the code changes because it's not going to be used anytime soon.

• Is there a kill switch to mitigate the impact immediately?
  Rollback.

[Shaddoll]

Does persistence tests cover the change?

[taylanisikdemir]

Does persistence tests cover the change?

They cover domain crud operations but not activeclusters field updates. let me add a few cases there