Restore the backup S3 host select box if an S3 target has been set

Also remove unnecessary import added in 7cda439c. Was a mistake from edits during PR review.

management/daemon.py

@@ -122,7 +122,6 @@ def index():
 	no_admins_exist = (len(get_admins(env)) == 0)
 
 	import boto3.s3
-	from urllib.parse import urlparse
 	backup_s3_hosts = [(r, f"s3.{r}.amazonaws.com") for r in boto3.session.Session().get_available_regions('s3')]
 
 

management/templates/system-backup.html

@@ -269,6 +269,7 @@ function show_custom_backup() {
           $("#backup-target-type").val("s3");
           var hostpath = r.target.substring(5).split('/');
           var host = hostpath.shift();
+          $("#backup-target-s3-host-select").val(host);
           $("#backup-target-s3-host").val(host);
           $("#backup-target-s3-path").val(hostpath.join('/'));
         } else if (r.target.substring(0, 5) == "b2://") {