[PLT-6496] Remove System Console and config settings for image height and width (#6688)

* remove System Console and config settings for image height and width

* add constants and update config.json

* updated as per review

config/config.json

@@ -113,12 +113,6 @@
         "Directory": "./data/",
         "EnablePublicLink": false,
         "PublicLinkSalt": "",
-        "ThumbnailWidth": 120,
-        "ThumbnailHeight": 100,
-        "PreviewWidth": 1024,
-        "PreviewHeight": 0,
-        "ProfileWidth": 128,
-        "ProfileHeight": 128,
         "InitialFont": "luximbi.ttf",
         "AmazonS3AccessKeyId": "",
         "AmazonS3SecretAccessKey": "",