MDEV-38046 Make func_regexp_pcre tolerant to PCRE2 offset change

PCRE2 10.47 reports the invalid escape in 'A\q' at offset 3 instead of 2.
Update the expected result and add a --replace_regex in the test so the
suite passes with both older and newer PCRE2 versions.

Author: aquilamacedo

mysql-test/main/func_regexp_pcre.result

@@ -791,7 +791,7 @@ SELECT 'AB' RLIKE 'A# this is a comment\nB';
 1
 SET default_regex_flags=DEFAULT;
 SELECT 'Aq' RLIKE 'A\\q';
-ERROR 42000: Regex error 'unrecognized character follows \ at offset 2'
+ERROR 42000: Regex error 'unrecognized character follows \ at offset 3'
 SET default_regex_flags='EXTRA';
 SELECT 'A' RLIKE 'B';
 'A' RLIKE 'B'

mysql-test/main/func_regexp_pcre.test

@@ -381,6 +381,8 @@ SELECT 'AB' RLIKE 'A B';
 SELECT 'AB' RLIKE 'A# this is a comment\nB';
 SET default_regex_flags=DEFAULT;
 
+# pcre2 versions differ in the reported error offset for invalid escapes
+--replace_regex /offset 2/offset 3/
 --error ER_REGEXP_ERROR
 SELECT 'Aq' RLIKE 'A\\q';