Pass omero.db.pass via envvar to bin/omero admin reindex

[sbesson]

For security reasons, the DB password is not passed as an xargs to the reindex
command. This commit fixes this issue by internally setting the JAVA_OPTS
environment variable which should only be visible to the process owner (and
root).

See https://www.openmicroscopy.org/community/viewtopic.php?f=5&t=7673&p=14962#p14952

To test this PR:

• set up a server with a user/password
• check bin/omero admin reindex --reset 0 fails without this PR
• check bin/omero admin reindex --reset 0 passes with this PR
• check JAVA_OPTS="-Dlogback.configurationFile=stderr.xml" bin/omero admin reindex --reset 0 passes with this PR
• in both cases above, check the environment variable does not leak for another user than the one doing the reindex (e.g. via ps auxe)

[ximenesuk]

This works okay, the problem I have is that it works without this PR too. Maybe that's some local problem.

[sbesson]

@ximenesuk: most likely, I had to modify my pg_hba.conf to force password checks as follows since default Homebrew installation will come with trust across the board.

# TYPE  DATABASE        USER            ADDRESS                 METHOD

# "local" is for Unix domain socket connections only
local   all             sebastien                                     trust
local   db_omero             db_user                                     md5
# IPv4 local connections:
host    all             sebastien             127.0.0.1/32            trust
host    all             db_user             127.0.0.1/32            md5
# IPv6 local connections:
host    all             sebastien             ::1/128                 trust
host    all             db_user             ::1/128                 md5

[manics]

bin/omero admin reindex --reset 0 fails on OMERO.server-5.0.5-ice35-b47, works on OMERO.server-5.1.0-m1-530-2e609f5-ice35-b321

[joshmoore]

Thank. Merging.

[sbesson]

--rebased-to #3171