[9.20] fix: nil: Fix parse_rr in lib/dns/skr.c was failing to reset the comments

If dns_name_fromtext failed or the subsequent dns_name_compare
failed the lexer's comments state wasn't cleaned up.

Closes #5564

Backport of MR !11088

Merge branch 'backport-5564-fix-bug-in-skr-c-parse_rr-on-error-path-9.20' into 'bind-9.20'

See merge request isc-projects/bind9!11091