A cleanup for MDEV-17511. Re-enabling ctype_ldml.test.

mysql-test/main/disabled.def

@@ -22,4 +22,3 @@ innodb_bug12902967       : broken upstream
 file_contents            : MDEV-6526 these files are not installed anymore
 max_statement_time       : cannot possibly work, depends on timing
 connect-abstract         : waiting for libmariadb update
-ctype_ldml               : MDEV-17511 revealed a wrong test

strings/ctype-uca.ic

@@ -625,14 +625,14 @@ MY_FUNCTION_NAME(strnxfrm)(CHARSET_INFO *cs,
     1. Keep trailing spaces as they are, so have strnxfrm_onelevel() scan
        spaces as normal characters. This will call scanner_next() for every
        trailing space and calculate its weight using UCA weights.
-    2. Strip trailing spaces before calling strnxfrm_onelevel().
-       If we return a too short key, the caller will append weights for
-       implicit spaces anyway, up to the desired key size.
+    2. Strip trailing spaces before calling strnxfrm_onelevel(), as it will
+       append weights for implicit spaces anyway, up to the desired key size.
        This will effectively generate exactly the same sortable key result.
     The latter is much faster.
   */
 
-  srclen= cs->cset->lengthsp(cs, (const char*) src, srclen);
+  if (flags & MY_STRXFRM_PAD_WITH_SPACE)
+    srclen= cs->cset->lengthsp(cs, (const char*) src, srclen);
   dst= MY_FUNCTION_NAME(strnxfrm_onelevel)(cs, &cs->uca->level[0],
                                            dst, de, nweights,
                                            src, srclen, flags);