More Accounts cleanup

* Remove `AccountStore`
* Clean up `AccountsDynamoDb#delete`
* Rename `AccountsDynamoDb` → `Accounts`
* Remove unused configuration
* Move Accounts scan page size to static configuration
* Remove disabled tests and related methods

service/src/test/java/org/whispersystems/textsecuregcm/configuration/dynamic/DynamicConfigurationTest.java

@@ -313,29 +313,6 @@ class DynamicConfigurationTest {
     }
   }
 
-  @Test
-  void testParseAccountsDynamoDbMigrationConfiguration() throws JsonProcessingException {
-    {
-      final String emptyConfigYaml = "test: true";
-      final DynamicConfiguration emptyConfig =
-          DynamicConfigurationManager.parseConfiguration(emptyConfigYaml).orElseThrow();
-
-      assertEquals(10, emptyConfig.getAccountsDynamoDbMigrationConfiguration().getDynamoCrawlerScanPageSize());
-    }
-
-    {
-      final String accountsDynamoDbMigrationConfig =
-          "accountsDynamoDbMigration:\n"
-              + "  dynamoCrawlerScanPageSize: 5000";
-
-      final DynamicAccountsDynamoDbMigrationConfiguration config =
-          DynamicConfigurationManager.parseConfiguration(accountsDynamoDbMigrationConfig).orElseThrow()
-              .getAccountsDynamoDbMigrationConfiguration();
-
-      assertEquals(5000, config.getDynamoCrawlerScanPageSize());
-    }
-  }
-
   @Test
   void testParseLimits() throws JsonProcessingException {
     {