Pick the *first* usable file type as the default, not the *last* one.

In wtap_get_savable_file_types_subtypes(), in the search for a default
file type to use, stop as soon as we've found a usable file type, don't
keep searching.

Bug: 14601
Change-Id: Iff4ffe14f5ad07271c49a761e0856059353c1634
Reviewed-on: https://code.wireshark.org/review/27193
Reviewed-by: Guy Harris <guy@alum.mit.edu>

wiretap/file_access.c

@@ -1893,6 +1893,7 @@ wtap_get_savable_file_types_subtypes(int file_type_subtype,
 						       required_comment_types)) {
 				/* OK, got it. */
 				default_file_type_subtype = ft;
+				break;
 			}
 		}
 	}