Remove zfs-zed hard dep from zfs-share init script

[beren12]

The zfs-share init script has a requires: dependency on zfs-zed. It doesn't seem to be needed to start, it's already in the "should start/stop" list, and it can break downstream packaging where zed is split from the main package: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=915831

the systemd scripts do not have this dependency listed either.

Motivation and Context

Debian splits off zed and the init system has troubles since there's a circ. dep.

Description

How Has This Been Tested?

Tested in debian stretch and works w/o issue

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Performance enhancement (non-breaking change which improves efficiency)
• Code cleanup (non-breaking change which makes code smaller or more readable)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation (a change to man pages or other documentation)

Checklist:

• My code follows the ZFS on Linux code style requirements.
• I have updated the documentation accordingly.
• I have read the contributing document.
• I have added tests to cover my changes.
• [x ] All new and existing tests passed.
• [x ] All commit messages are properly formatted and contain Signed-off-by.

[codecov]

Codecov Report

Merging #8447 into master will increase coverage by 0.03%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #8447      +/-   ##
==========================================
+ Coverage   78.56%    78.6%   +0.03%     
==========================================
  Files         380      380              
  Lines      116001   116003       +2     
==========================================
+ Hits        91137    91179      +42     
+ Misses      24864    24824      -40

Flag	Coverage Δ
#kernel	79.04% <ø> (ø)	⬆️
#user	67.27% <ø> (-0.19%)	⬇️

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[bunder2015]

gentoo doesn't seem to use these for dependency tracking (we use rc_need), but in theory we shouldn't need zed to share datasets.