tests/qtest: bump up QOS_PATH_MAX_ELEMENT_SIZE

tests/qtest: bump up QOS_PATH_MAX_ELEMENT_SIZE

It seems the depth of stack we need to support can vary depending on
the order of the init constructors getting called. It seems
--enable-lto shuffles things around just enough to push you over the
limit.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Fixes: https://gitlab.com/qemu-project/qemu/-/issues/1186
Acked-by: Thomas Huth <thuth@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220929114231.583801-12-alex.bennee@linaro.org>