Yahpo blackbox not matching direct calls to yahpo

[sighellan]

Describe the bug
When not explicitly giving the fidelity in the YAHPO wrapper, we get different values than when calling YAHPO directly. Related to #437, but for when fidelity variable is None

To reproduce

import yahpo_gym
from syne_tune.blackbox_repository import BlackboxRepositoryBackend

yahpo_dataset = '4134'

# syne-tune set-up
backend = BlackboxRepositoryBackend(
                blackbox_name="yahpo-rbv2_svm",
                elapsed_time_attr="timetrain",
                dataset=yahpo_dataset,
                surrogate_kwargs={'fidelities': [1]}
)


# Example config to compare
raw_config = {
    'cost': 1.0,
    'kernel': 'linear',
    'num.impute.selected.cpo': 'impute.mean',
    'task_id': '4134',
    'tolerance': 0.009528896028657764,
    'degree': 4,
    'gamma': 1.0,
    'repl': 10,
    'trainsize': 0.05
}

conf_syne_tune = {hp: raw_config[hp] for hp in raw_config if hp != 'trainsize'}
conf_syne_tune_v2 = {hp: raw_config[hp] for hp in raw_config if hp not in ['trainsize', 'degree', 'gamma']}

conf_yahpo = {hp: raw_config[hp] for hp in raw_config if hp not in ['degree', 'gamma']}

print(backend.blackbox(conf_syne_tune))
print(backend.blackbox(conf_syne_tune_v2))

# YAHPO set-up
bb = yahpo_gym.BenchmarkSet(scenario="rbv2_svm")
bb.set_instance(yahpo_dataset)


print(bb.objective_function(conf_yahpo))

Output:

[[ 1.00000000e+00  1.00000000e+00  1.00000000e+00  1.29179525e+00
  -5.96046448e-08  8.45990071e-05  9.97874737e-02  2.09929701e-02
  -2.62584304e-04]]
[[ 0.65576935  0.62228823  0.67812222  0.21296407  0.61258245  0.68215483
  10.71848392  3.69341993  0.35094392]]
[{'acc': 0.65576935, 'bac': 0.6222882, 'auc': 0.6781222, 'brier': 0.21296407, 'f1': 0.61258245, 'logloss': 0.68215483, 'timetrain': 10.718484, 'timepredict': 3.69342, 'memory': 0.35094392}]

Expected behavior
A clear and concise description of what you expected to happen.

Would expect the metrics to match those of YAHPO.

Paste the output of the pip freeze command below:

Desktop (please complete the following information):

• OS: [e.g. MacOS Monterey 12.6.1 / Ubuntu Linux / Windows 11]
• Syne Tune Version main (5ccdef4)

Screenshots
If applicable, add screenshots to help explain your problem.

Additional context
Add any other context about the problem here.