[run-benchmark][GTK][WPE] Add support for auto-entering container SDK when running minibrowser

https://bugs.webkit.org/show_bug.cgi?id=319511

Reviewed by Adrian Perez de Castro.

When executing the script run-benchmark outside of the container SDK but with
the auto-entering mechanism enabled it happens that the script first sets a
temporal random homedir and then calls run-minibrowser script. Then the script
run-minibrowser tries to auto-enter into the container, but since it has been
started with a temporal random empty home it can't find the podman image, so
it has to re-download again the huge image on a temporal dir. And it has to
do that anytime is invoked because the homedir changes from one invocation
to the next one.

To avoid this problem we can auto-enter into the container in run-benchmark
before executing the script run-minibrowser. But we should do this only when
the browser to run is minibrowser-gtk or minibrowser-wpe. Otherwise we would be
entering into the container to execute browsers like chrome or firefox which
are not available in the container SDK.

* Tools/Scripts/webkitpy/benchmark_runner/run_benchmark.py:
(start):

Canonical link: https://commits.webkit.org/317280@main