Prevent null unicode character errors during the migration (#26974)

server/tests/template.load

@@ -4,7 +4,8 @@ LOAD DATABASE
 
 WITH data only,
     workers = 8, concurrency = 1,
-     multiple readers per thread, rows per range = 50000,
+    multiple readers per thread, rows per range = 10000,
+    prefetch rows = 10000, batch rows = 2500,
     create no tables, create no indexes,
     preserve index names
 
@@ -16,22 +17,24 @@ SET MySQL PARAMETERS
     net_read_timeout  = '120',
     net_write_timeout = '120'
 
-CAST column Channels.Type to "channel_type" drop typemod,
+ CAST column Channels.Type to "channel_type" drop typemod,
     column Teams.Type to "team_type" drop typemod,
     column UploadSessions.Type to "upload_session_type" drop typemod,
+    column ChannelBookmarks.Type to "channel_bookmark_type" drop typemod,
     column Drafts.Priority to text,
     type int when (= precision 11) to integer drop typemod,
     type bigint when (= precision 20) to bigint drop typemod,
-     type text to varchar drop typemod,
+    type text to varchar drop typemod using remove-null-characters,
     type tinyint when (<= precision 4) to boolean using tinyint-to-boolean,
-     type json to jsonb drop typemod
+    type json to jsonb drop typemod using remove-null-characters
 
 EXCLUDING TABLE NAMES MATCHING ~<IR_>, ~<focalboard>
 
 BEFORE LOAD DO
     $$ ALTER SCHEMA public RENAME TO {{ .source_schema }}; $$,
-     $$ DROP INDEX IF EXISTS idx_posts_message_txt; $$,
+    $$ TRUNCATE TABLE {{ .source_schema }}.systems; $$,
-     $$ DROP INDEX IF EXISTS idx_fileinfo_content_txt; $$
+    $$ DROP INDEX IF EXISTS {{ .source_schema }}.idx_posts_message_txt; $$,
+    $$ DROP INDEX IF EXISTS {{ .source_schema }}.idx_fileinfo_content_txt; $$
 
 AFTER LOAD DO
      $$ UPDATE {{ .source_schema }}.db_migrations set name='add_createat_to_teamembers' where version=92; $$,