dnsapi/deploy: remove POSIX character classes from sed/grep patterns
Solaris /usr/bin/sed and /usr/bin/grep parse [[:space:]] etc. as a
literal bracket set and silently mis-match. Replace with [ ]* for
JSON matching, a printf-tab bracket for user-input trimming, and
[0-9] for digits; also drop GNU-only sed -r/-E in rage4, selfhost
and selectel, and reuse _strip_blank_lines in byteplus_alb.
