sockstat: improve handling of path state

Only suppress the path state column when producing traditional text
output. When generating html output, always include the column.
Please note that when generating json or xml output, optional fields
like the path state are only generated if they is applicable. This
has not been changed.
The changes in this patch were suggested by asomers.

Reviewed by: asomers
Fixes: 746eadecaa7d ("sockstat: show path state column only when useful")
Sponsored by: Netflix, Inc.
Differential Revision: https://reviews.freebsd.org/D53005

(cherry picked from commit 97e858f5b335ae8f98619f9cee8ab9a0501cd06d)