/bin/sh is not always bash. In distributions like Mobian where /bin/sh does not
have bash features, startplasmamobile outputs "[[: command not found" or similar
message because of the use of '[[' on the if statement that looks for
systemd-coredump.
startplasma-waylandsession hasn't existed for a while and the whole
session launched just fine without it, so let's remove the entire
argument.
The binary was removed in plasma-workspace in 7884f53d3c07699dc16f07cf0aa3966802c503c8
