[MySQL] az mysql flexible-server backup delete: Support deletion of on-demand backup (#32498)

Author: honghr

src/azure-cli/azure/cli/command_modules/mysql/_help.py

@@ -785,6 +785,14 @@
     text: az mysql flexible-server backup create -g testgroup -n testsvr --backup-name testbackup
 """
 
+helps['mysql flexible-server backup delete'] = """
+type: command
+short-summary: Delete a backup for a given server with specified backup name.
+examples:
+  - name: Delete a backup for 'testsvr' with backup name 'testbackup'.
+    text: az mysql flexible-server backup delete -g testgroup -n testsvr --backup-name testbackup
+"""
+
 helps['mysql flexible-server identity'] = """
 type: group
 short-summary: Manage server user assigned identities.

src/azure-cli/azure/cli/command_modules/mysql/_params.py

@@ -633,8 +633,15 @@ def load_arguments(self, _):    # pylint: disable=too-many-statements, too-many-
     with self.argument_context('mysql flexible-server backup create') as c:
         c.argument('backup_name', options_list=['--backup-name', '-b'], help='The name of the new backup.')
 
+    with self.argument_context('mysql flexible-server backup delete') as c:
+        c.argument('resource_group_name', arg_type=resource_group_name_type)
+        c.argument('server_name', id_part=None, arg_type=server_name_arg_type)
+        c.argument('backup_name', options_list=['--backup-name', '-b'], help='The name of the backup.')
+
     with self.argument_context('mysql flexible-server backup show') as c:
-        c.argument('backup_name', id_part='child_name_1', options_list=['--backup-name', '-b'], help='The name of the backup.')
+        c.argument('resource_group_name', arg_type=resource_group_name_type)
+        c.argument('server_name', id_part=None, arg_type=server_name_arg_type)
+        c.argument('backup_name', options_list=['--backup-name', '-b'], help='The name of the backup.')
 
     with self.argument_context('mysql flexible-server backup list') as c:
         c.argument('server_name', id_part=None, arg_type=server_name_arg_type)

src/azure-cli/azure/cli/command_modules/mysql/commands.py

@@ -194,6 +194,7 @@ def load_command_table(self, _):
     with self.command_group('mysql flexible-server backup', mysql_flexible_long_running_backup_sdk,
                             client_factory=cf_mysql_flexible_backup) as g:
         g.command('create', 'begin_create')
+        g.command('delete', 'begin_delete')
 
     with self.command_group('mysql flexible-server backup', mysql_flexible_long_running_backups_sdk,
                             client_factory=cf_mysql_flexible_backups) as g: