Now that the enterprise version of GPDB is only provided via RPM, including
gpseginstall in the distribution would cause conflicts if users try to install
GPDB with RPMs and with gpseginstall on the same cluster.  While it could be
preserved for use by the OSS community, there are several standard tools for
copying GPDB files to segment hosts in a cluster, and recommendations for using
one or more of those tools will be included in the GPDB documentation.

In addition to removing gpseginstall itself, this commit removes references to
it in other utilities' documentation and removes code in gppylib that was only
called by gpseginstall.
Co-authored-by: NJamie McAtamney <jmcatamney@pivotal.io>
Co-authored-by: NKalen Krempely <kkrempely@pivotal.io>
(cherry picked from commit 64014685)

Any code dealing with replication ports was removed in previous commits; this
commit removes lingering references in comments and help text.
Co-authored-by: NJamie McAtamney <jmcatamney@pivotal.io>
Co-authored-by: NMark Sliva <msliva@pivotal.io>

(cherry picked from commit 813528e7)

There was a lot of unused code in the gpMgmt bash code that hasn't
been running for quite some time. On top of really dead code, some
codepaths were reachable, but useless (like printing a non-existing
version string). Remove the dead code and replace the version print
with working code which pulls the version from the canonical source.

The option description should aptly describe what the option is and
how it's used, a shorter version is not required. Also, the short
version could be mistaken for a parameter to pass in on a quick eye
so remove.