MEDIUM: stick-table: remove the now duplicate find_stktable() function

Since proxy_tbl_by_name() already does the same job, let's not keep
duplicate functions and use this one only.
diff --git a/src/cfgparse.c b/src/cfgparse.c
index 778edf7..1de7a1f 100644
--- a/src/cfgparse.c
+++ b/src/cfgparse.c
@@ -3461,7 +3461,7 @@
 		int myidx = 1;
 		struct proxy *other;
 
-		other = find_stktable(curproxy->id);
+		other = proxy_tbl_by_name(curproxy->id);
 		if (other) {
 			Alert("parsing [%s:%d] : stick-table name '%s' conflicts with table declared in %s '%s' at %s:%d.\n",
 			      file, linenum, curproxy->id, proxy_type_str(other), other->id, other->conf.file, other->conf.line);