dbus-daemon test: Don't test fd limits if in an unprivileged container

In an unprivileged container, uid 0 doesn't have CAP_SYS_RESOURCE, so
we can't expect the dbus-daemon to be able to escalate its fd limit.

This can be reproduced using bubblewrap:

    sudo bwrap \
        --cap-drop CAP_SYS_RESOURCE \
        --ro-bind / / \
        --dev /dev \
    env \
        DBUS_TEST_DAEMON=.../bus/dbus-daemon \
        DBUS_TEST_DATA=.../test/data \
    .../test/test-dbus-daemon \
        -p /fd-limit \
        --verbose

Bug-Debian: https://bugs.debian.org/908092
12 jobs for unprivileged-container in 0 seconds (queued for 99 minutes and 22 seconds)
Status Job ID Name Coverage
  Build
manual #55933
allowed to fail manual
build:buster
failed #55927
build:cmake

failed #55924
build:debug

manual #55929
allowed to fail manual
build:i686-w64-mingw32-cmake
failed #55928
build:i686-w64-mingw32-debug

manual #55932
allowed to fail manual
build:jessie
manual #55926
allowed to fail manual
build:legacy
failed #55923
build:production

manual #55925
allowed to fail manual
build:reduced
failed #55930
build:x86_64-w64-mingw32

failed #55931
build:x86_64-w64-mingw32-cmake-debug

manual #55934
allowed to fail manual
build:xenial
 
Name Stage Failure
failed
build:x86_64-w64-mingw32-cmake-debug Build There has been a timeout failure or the job got stuck. Check your timeout limits or try again
No job log
failed
build:x86_64-w64-mingw32 Build There has been a timeout failure or the job got stuck. Check your timeout limits or try again
No job log
failed
build:i686-w64-mingw32-debug Build There has been a timeout failure or the job got stuck. Check your timeout limits or try again
No job log
failed
build:cmake Build There has been a timeout failure or the job got stuck. Check your timeout limits or try again
No job log
failed
build:debug Build There has been a timeout failure or the job got stuck. Check your timeout limits or try again
No job log
failed
build:production Build There has been a timeout failure or the job got stuck. Check your timeout limits or try again
No job log