Bugfix: Weird behaviour after switching users (rebased onto dev_5_0)

[dominikl]

This is the same as gh-2189 but rebased onto dev_5_0.

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After switching users new service adapter instances were created but never passed on to the registry, so subsequent calls to the server picked up old service adapter instances, with the old OMEROGateway which still used the session created by the previous user.

Fix for: https://trac.openmicroscopy.org.uk/ome/ticket/12055
Should also fix other issues due to switching users

To Test: Follow the scenario mentioned in the ticket above;

[dominikl]

--rebased-from #2189

[gusferguson]

@dominikl @jburel

Testing using OMERO.insight-5.0.0-175-2d7453e-ice33-b612-mac on gretzky.
Logged in as user 6 switched to read-only-1 - started to do an import-as user-3 - while this still under way started import-as user-9.
Insight crashed with loss of connection error alert.
Bug ticket: https://trac.openmicroscopy.org.uk/ome/ticket/12125
This was reproducible.
When repeated and I allowed the user-3 import-as to complete before starting the user-9 import-as then did not have crash.
Data imported as expected with correct ownership.
If import as user-6 (self) and then the second import-as done as user-9 this is successful and does not cause crash.
Data imported as expected with correct ownership.
If data is imported without creating new folder, but just as orphaned dataset from file name (i.e. default) then the crash does not occur and import-as takes place as expected.
So it seems to be the creation of the new folders that is causing the crash, even though the ownership of the projects and dat sets created on import-as are correctly for the import-as user.

Used "Switch user" to logout as user-9 and logged in as user-3.
In read-only-1 (user-3 is owner) could correctly import as self to own projects and datasets, but could also import to user-9's - I am not clear if this should be possible as owner of the group - I thought not but I may be misunderstanding the permissions.
The owner of the data imported into user-9s dataset remained user-3.

Used "Switch user" to logout as user-3 and logged in as user-2.
In read-only-1 (ordinary member) user-2 could not import into other user's projects or datasets - as expected.
Importing as user-2 into own project and dataset ownership was user-2 as expected.

Used "Switch user" to logout as user-2 and logged in as user-6.
Behaves as expected - can import as self and other users into read-annotate-1 and read-only-1 one with correct ownership as long as new projects are not created with concurrent import-as.
Again reproduced crash in read-annotate-1 with concurrent import-as.

Conclusion:
It looks as if the "Switch user" weirdness this PR is aimed at has been successfully addressed, but something has affected the functioning of import-as - can't tell if it is this PR.
I would suggest not merging until this is investigated further.

Screenshots:

[jburel]

@dominikl, @gusferguson: sorry for not replying earlier. The problem highlighted by @gusferguson is not related to the changes introduced by this PR see gh-2225.

[joshmoore]

i.e. "good to go"?

[joshmoore]

ping

[dominikl]

For me, yes, good to go. If there are no other objections?

[joshmoore]

Perfect, thanks.