docs: reorder collation regression test order in paragraph

Backpatch-through: 10

doc/src/sgml/regress.sgml

@@ -318,7 +318,7 @@ make check EXTRA_TESTS=numeric_big
 </screen>
     To run the collation tests:
 <screen>
-make check EXTRA_TESTS='collate.icu.utf8 collate.linux.utf8' LANG=en_US.utf8
+make check EXTRA_TESTS='collate.linux.utf8 collate.icu.utf8' LANG=en_US.utf8
 </screen>
     The <literal>collate.linux.utf8</literal> test works only on Linux/glibc
     platforms.  The <literal>collate.icu.utf8</literal> test only works when