fix: reduced string length for innodb 5.6

[NiklasSchmitt]

error while installation:

{"reqId":"0YbMH1Fd40D73AzYk0fG","level":3,"time":"2022-05-27T21:57:32+00:00","remoteAddr":"185.66.193.120","user":"Niklas","app":"settings","method":"POST","url":"/settings/apps/enable","message":"could not enable apps","userAgent":"Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:100.0) Gecko/20100101 Firefox/100.0","version":"24.0.1.1","exception":{"Exception":"InvalidArgumentException","Message":"Column \"oc_reader_bookmarks\".\"content\" is type String, but exceeding the 4.000 length limit.","Code":0,"Trace":[{"file":"/var/www/html/lib/private/DB/MigrationService.php","line":461,"function":"ensureOracleConstraints","class":"OC\\DB\\MigrationService","type":"->","args":[{"__class__":"Doctrine\\DBAL\\Schema\\Schema"},{"__class__":"Doctrine\\DBAL\\Schema\\Schema"},3]},{"file":"/var/www/html/lib/private/DB/MigrationService.php","line":417,"function":"migrateSchemaOnly","class":"OC\\DB\\MigrationService","type":"->","args":["latest"]},{"file":"/var/www/html/lib/private/Installer.php","line":154,"function":"migrate","class":"OC\\DB\\MigrationService","type":"->","args":["latest",true]},{"file":"/var/www/html/apps/settings/lib/Controller/AppSettingsController.php","line":451,"function":"installApp","class":"OC\\Installer","type":"->","args":["epubreader"]},{"file":"/var/www/html/lib/private/AppFramework/Http/Dispatcher.php","line":225,"function":"enableApps","class":"OCA\\Settings\\Controller\\AppSettingsController","type":"->","args":[["epubreader"],[]]},{"file":"/var/www/html/lib/private/AppFramework/Http/Dispatcher.php","line":133,"function":"executeController","class":"OC\\AppFramework\\Http\\Dispatcher","type":"->","args":[{"__class__":"OCA\\Settings\\Controller\\AppSettingsController"},"enableApps"]},{"file":"/var/www/html/lib/private/AppFramework/App.php","line":172,"function":"dispatch","class":"OC\\AppFramework\\Http\\Dispatcher","type":"->","args":[{"__class__":"OCA\\Settings\\Controller\\AppSettingsController"},"enableApps"]},{"file":"/var/www/html/lib/private/Route/Router.php","line":298,"function":"main","class":"OC\\AppFramework\\App","type":"::","args":["OCA\\Settings\\Controller\\AppSettingsController","enableApps",{"__class__":"OC\\AppFramework\\DependencyInjection\\DIContainer"},{"_route":"settings.AppSettings.enableApps"}]},{"file":"/var/www/html/lib/base.php","line":1023,"function":"match","class":"OC\\Route\\Router","type":"->","args":["/settings/apps/enable"]},{"file":"/var/www/html/index.php","line":36,"function":"handleRequest","class":"OC","type":"::","args":[]}],"File":"/var/www/html/lib/private/DB/MigrationService.php","Line":613,"CustomMessage":"could not enable apps"}}

I've changed length of strings from 4096 back to 4000 for supporting a installation of this app on innodb 5.6 databases.
see here for reference: https://dev.mysql.com/doc/refman/5.6/en/innodb-limits.html

[fossil-free]

Could this pull request be merged? Installing ebookreader fails for me in our NC 24 with the error message:
"Column "oc_reader_bookmarks"."content" is type String, but exceeding the 4.000 length limit."
(I don't know whether we use an innodb database though).

[Emiliaaah]

I'm also asking for this to be merged. This seems to also fix the issue for me.

[DerBoki]

Definitely fixed it for me today. Please merge this, so everybody can enjoy it in NC24. :)

[borekon]

Developers are missing...

[markuman]

@e-alfred do you have time to target this one?