MDEV-22741: *SAN: ERROR: AddressSanitizer: use-after-poison on address in instrings/strmake.c:36 from change_master (on optimized builds)

Problem:
========
CHANGE MASTER TO MASTER_USER='root', MASTER_SSL=0, MASTER_SSL_CA='',
  MASTER_SSL_CERT='', MASTER_SSL_KEY='', MASTER_SSL_CRL='',
  MASTER_SSL_CRLPATH='';

CHANGE MASTER TO MASTER_USER='root', MASTER_PASSWORD='', MASTER_SSL=0;

use-after-poison is reported for lex_mi->ssl_crl

File: sql_repl.cc

if (lex_mi->ssl_crl)
  strmake_buf(mi->ssl_crl, lex_mi->ssl_crl);

Analysis:
========
At the end of CHANGE MASTER statement execution, the LEX_MASTER_INFO
parameters are reset so that the next query will have a clean state. But
'ssl_crl' and 'ssl_crl_path' members of LEX_MASTER_INFO object are not
cleared during 'LEX_MASTER_INFO::reset'. Hence when a new CHANGE MASTER
statement is executed, the stale value of lex_mi->ssl_crl is used, so ASAN
reports use-after-poison.

Fix:
===
Clear 'ssl_crl' and 'ssl_crl_path' as part of 'reset'.