shells/fish: update to 3.7.1 and fix Makefile

• Update to fish 3.7.1.
• Remove zfs feature check patch; included upstream.
• Remove post install step to strip binaries; binaries are stripped durting install.
• Add post install steps to remove documentation and/or manual pages if DOCS and/or MANPAGES are not enabled. Be default fish always installs documentation and manual pages.

PR: 278468
Approved by: asomers (maintainer)