fix: make sure to use unaltered fields when saving a shadow copy for updated profiles or comments (#8533)

Follow-up of !6977

### Manual testing
- User **S** creates an organization **O** and posts a comment **C** (on a random issue);
- User **R** report as abuse the comment **C**, the organization **O** as well as the user **S**;
- User **S** changes the content of comment **C** and the description of organization **O** as well as the description of their own profile;
- Check (within DB) that shadow copies are being created (and linked to corresponding abuse reports) for comment **C**, organization **O** and user **S** and the content is the one from the moment when the reports were submitted (therefore before the updates made by **S**).

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/8533
Reviewed-by: Gusted <gusted@noreply.codeberg.org>
Co-authored-by: floss4good <floss4good@disroot.org>
Co-committed-by: floss4good <floss4good@disroot.org>

models/user/user.go

@@ -927,7 +927,9 @@ func UpdateUserCols(ctx context.Context, u *User, cols ...string) error {
 
 	// If the user was reported as abusive and any of the columns being updated is relevant
 	// for moderation purposes a shadow copy should be created before first update.
-	if err := IfNeededCreateShadowCopyForUser(ctx, u, cols...); err != nil {
+	// Since u is already altered at this point we are sending nil instead as an argument
+	// so that the unaltered version will be retrieved from DB.
+	if err := IfNeededCreateShadowCopyForUser(ctx, u.ID, nil, cols...); err != nil {
 		return err
 	}