set warn*recip in spamfilter_policy defaults

I got an sql error (on a slave nameserver, fwiw) on resync of mailfilters because of how the resync tool generates the REINSERT query.

ns2.slave.server.ns - 27.11.2020-18:06 - WARNING - Falsche Anfrage / Wrong QuerySQL-Query = REPLACE INTO `spamfilter_policy` (`id`,`sys_userid`,`sys_groupid`,`sys_perm_user`,`sys_perm_group`,`sys_perm_other`,`policy_name`,`virus_lover`,`spam_lover`,`banned_files_lover`,`bad_header_lover`,`bypass_virus_checks`,`bypass_spam_checks`,`bypass_banned_checks`,`bypass_header_checks`,`spam_modifies_subj`,`virus_quarantine_to`,`spam_quarantine_to`,`banned_quarantine_to`,`bad_header_quarantine_to`,`clean_quarantine_to`,`other_quarantine_to`,`spam_tag_level`,`spam_tag2_level`,`spam_kill_level`,`spam_dsn_cutoff_level`,`spam_quarantine_cutoff_level`,`addr_extension_virus`,`addr_extension_spam`,`addr_extension_banned`,`addr_extension_bad_header`,`warnvirusrecip`,`warnbannedrecip`,`warnbadhrecip`,`newvirus_admin`,`virus_admin`,`banned_admin`,`bad_header_admin`,`spam_admin`,`spam_subject_tag`,`spam_subject_tag2`,`message_size_limit`,`banned_rulenames`,`policyd_quota_in`,`policyd_quota_in_period`,`policyd_quota_out`,`policyd_quota_out_period`,`policyd_greylist`,`rspamd_greylisting`,`rspamd_spam_greylisting_level`,`rspamd_spam_tag_level`,`rspamd_spam_tag_method`,`rspamd_spam_kill_level`) VALUES ('4','1','0','riud','riud','r','Wants viruses','Y','N','Y','Y','N','N','N','N','Y',NULL,NULL,NULL,NULL,NULL,NULL,'3.00','6.90','6.90',NULL,NULL,NULL,NULL,NULL,NULL,'','','',NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,'-1','24','-1','24','N','y','4.00','6.00','rewrite_subject','10.00') -> 1265 (Data truncated for column 'warnvirusrecip' at row 1)