Limit Qt and OpenSSL Library pathes to the install directory

Once upon a time, the SyncEngine was instantiated once per sync. But now that
the SyncEngine is kept between sync, we need to reset all these variable between
syncs.

Reverts commit 622017ad

Could be the cause of #5092 and the cost is higher than the benefit if this is the case.
A network request taking more than 30 seconds isn't something unlikely in this world
and shouldn't be a good reason to abort. We should try to untangle the threads
dependencies to properly fix this if possible instead.

[2.2] Add Jenkinsfile (#5041)

Issue #5069

(cherry picked from commit 927a8b50 and
a4310f0f)

Also include a minor change from #5025

The changes in build location were only done on the x64 configuration.

It opens a window and connects to a cipher test
page, showing the output from there, that helps for debugging.

The window is enabled by setting the environment variable
OWNCLOUD_SHIBBOLETH_DEBUG