install-deps.sh: fix install-deps script for focal and bionic

install-deps.sh: fix install-deps script for focal and bionic

When run on focal and bionic, install-deps ends early
due to this extra debug message that was added to the
end of `ensure_decent_gcc_on_ubuntu`. The debug message
prints when the script is run in a jenkins environment.

When the script is not run in a jenkins environment, the
value returned there is "false" or "0", which acts as
an early return. This stops the script from completing.

We can remove this line, as `ensure_decent_gcc_on_ubuntu`
is only called for focal and bionic, and most of the jenkins
nodes are running jammy. Also, there is a debug message at the
beginning of the function that should suffice.

Fixes: https://tracker.ceph.com/issues/57466
Signed-off-by: Laura Flores <lflores@redhat.com>