[Postgres] Fix replication slot name (#226)

* Use slot_name from replication connection.

* Add changeset.

Author: rkistner

Diff for: .changeset/cyan-otters-sleep.md

@@ -0,0 +1,5 @@
+---
+'@powersync/service-core': patch
+---
+
+Use slot_name_prefix from the replication connection again.

Diff for: packages/service-core/src/util/config/compound-config-collector.ts

@@ -170,8 +170,7 @@ export class CompoundConfigCollector {
           baseConfig.api?.parameters?.max_data_fetch_concurrency ?? DEFAULT_MAX_DATA_FETCH_CONCURRENCY
       },
       // TODO maybe move this out of the connection or something
-      // slot_name_prefix: connections[0]?.slot_name_prefix ?? 'powersync_'
-      slot_name_prefix: 'powersync_',
+      slot_name_prefix: baseConfig.replication?.connections?.[0]?.slot_name_prefix ?? 'powersync_',
       parameters: baseConfig.parameters ?? {}
     };