MM-9661: tweak post message size log (#8517)

Call out the number of supported characters explicitly, moving the byte
limit to parentheses.

i18n/en.json

@@ -6512,7 +6512,7 @@
   },
   {
     "id": "store.sql_post.query_max_post_size.max_post_size_bytes",
-    "translation": "Post.Message supports at most %d bytes"
+    "translation": "Post.Message supports at most %d characters (%d bytes)"
   },
   {
     "id": "store.sql_post.query_max_post_size.unrecognized_driver",

store/sqlstore/post_store.go

@@ -1269,8 +1269,6 @@ func (s *SqlPostStore) determineMaxPostSize() int {
 		l4g.Warn(utils.T("store.sql_post.query_max_post_size.unrecognized_driver"))
 	}
 
-	l4g.Trace(utils.T("store.sql_post.query_max_post_size.max_post_size_bytes"), maxPostSizeBytes)
-
 	// Assume a worst-case representation of four bytes per rune.
 	maxPostSize = int(maxPostSizeBytes) / 4
 
@@ -1281,6 +1279,8 @@ func (s *SqlPostStore) determineMaxPostSize() int {
 		maxPostSize = model.POST_MESSAGE_MAX_RUNES_V1
 	}
 
+	l4g.Info(utils.T("store.sql_post.query_max_post_size.max_post_size_bytes"), maxPostSize, maxPostSizeBytes)
+
 	return maxPostSize
 }