tests: fix failing e2e tests

[tswast]

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Fixes #<issue_number_goes_here> 🦕

[tswast]

TODO: Might be better to replace this test with a unit test where we verify that we're actually sending VPC info in the relevant requests.

[tswast]

Removed this test, as it's redundant with the check here:

python-bigquery-dataframes/tests/system/large/test_remote_function.py

Line 1426 in 72e9583

assert gcf.service_config.vpc_connector == gcf_vpc_connector

[tswast]

e2e nox session is now succeeding. Regarding the doctest failures, it looks like maybe we aren't correctly installing from source? The failures are for TypeError: remote_function() missing 2 required positional arguments: 'input_types' and 'output_type' which should both be optional arguments as of #717

Filed internal issue 343447415 to investigate.

=========================== short test summary info ============================
FAILED third_party/bigframes_vendored/pandas/core/frame.py::frame.DataFrame.map
FAILED third_party/bigframes_vendored/pandas/core/frame.py::frame.DataFrame.apply
FAILED third_party/bigframes_vendored/pandas/core/series.py::series.Series.mask
FAILED third_party/bigframes_vendored/pandas/core/series.py::series.Series.apply
FAILED third_party/bigframes_vendored/pandas/core/series.py::series.Series.map
FAILED bigframes/dataframe.py::bigframes.dataframe.DataFrame.applymap
FAILED bigframes/dataframe.py::bigframes.dataframe.DataFrame.map
7 failed, 455 passed, 89 warnings in 491.39s (0:08:11)
nox > Command py.test --quiet -n=20 --timeout=900 --durations=20 --junitxml=doctest_3.12_sponge_log.xml --cov=bigframes --cov=bigframes --cov-append --cov-config=.coveragerc --cov-report=term-missing --cov-fail-under=0 --doctest-modules third_party bigframes failed with exit code 1
nox > Session doctest failed.
nox > Ran multiple sessions:
nox > * e2e: success
nox > * doctest: failed