Remove unnecessary backslash from CopyFrom() code.

Commit 4ac2a9b accidentally added an unnecessary backslash
to CopyFrom() code. This commit removes it.

Author: Yugo Nagata
Reviewed-by: Tender Wang
Discussion: https://postgr.es/m/20241112114609.4175a2e175282edd1463dbc6@sraoss.co.jp

Author: MasaoFujii

src/backend/commands/copyfrom.c

@@ -1018,7 +1018,7 @@ CopyFrom(CopyFromState cstate)
 			pgstat_progress_update_param(PROGRESS_COPY_TUPLES_SKIPPED,
 										 cstate->num_errors);
 
-			if (cstate->opts.reject_limit > 0 && \
+			if (cstate->opts.reject_limit > 0 &&
 				cstate->num_errors > cstate->opts.reject_limit)
 				ereport(ERROR,
 						(errcode(ERRCODE_INVALID_TEXT_REPRESENTATION),