fix(executor): remove old workaround for Apple silicon

After the recent upgrade of rules_python the bootstrap script is no longer able to run under sh.

It appears that the bootstrap script used in rules_python got some updates between 1.2.0 and 1.6.3 that made it trigger a syntax error when being run through sh:

ERROR: test/plans/mvp/BUILD.bazel:76:9: LabGridRunBinary test/plans/mvp/MVP_SCENARIO_3_LOCALHOST-process-results.xml failed: (Exit 2): executor failed: error executing LabGridRunBinary command (from target //test/plans/mvp:MVP_SCENARIO_3_LOCALHOST-process)
  (cd /private/var/tmp/_bazel_frepau01/a8505e41777f0f22188f118439f95722/sandbox/darwin-sandbox/32/execroot/_main && \
  exec env - \
    ARTIFACTORY_API_KEY='' \
    ARTIFACTORY_USER_EMAIL='' \
    MONGO_TLS_CA_FILE=/usr/local/share/ca-certificates/global-bundle.crt \
    PATH=/bin:/usr/bin:/usr/local/bin \
    PYTHONUNBUFFERED=1 \
  bazel-out/darwin_x86_64-opt-exec-ST-4b216e2ffc40/bin/external/rules_labgrid+/labgrid/executor/executor -- bazel-out/darwin_x86_64-opt-exec-ST-4b216e2ffc40/bin/system_tests/main-process --test-cases system_tests.implementations.test_cases.mvp.mvp.MvpTestCase --result-format junit --result-file bazel-out/darwin_x86_64-fastbuild-ST-65718626ef9b/bin/test/plans/mvp/MVP_SCENARIO_3_LOCALHOST-process-results.xml --output-workspace bazel-out/darwin_x86_64-fastbuild-ST-65718626ef9b/bin/test/plans/mvp/MVP_SCENARIO_3_LOCALHOST-process-workspace --no-bad-exit --testcase-parameters bazel-out/darwin_x86_64-fastbuild-ST-65718626ef9b/bin/test/plans/mvp/MVP_SCENARIO_3_LOCALHOST-process-testcase_parameters.json --platform-parameters bazel-out/darwin_x86_64-fastbuild-ST-65718626ef9b/bin/test/plans/mvp/MVP_SCENARIO_3_LOCALHOST-process-platform_parameters.json --downloads bazel-out/darwin_x86_64-fastbuild-ST-65718626ef9b/bin/test/plans/mvp/MVP_SCENARIO_3_LOCALHOST-process-downloads.json --console-logging-level debug --input-workspace bazel-out/darwin_x86_64-fastbuild-ST-65718626ef9b/bin/test/plans/mvp/MVP_SCENARIO_3_LOCALHOST-preprocess-workspace process)
# Configuration: 5b19d3d3ba93d4d7bcdeb0698866ff2ecb46ade224e4b6afe7ff3d07b833353c
# Execution platform: @@platforms//host:host

Use --sandbox_debug to see verbose messages from the sandbox and retain the sandbox build root for debugging
bazel-out/darwin_x86_64-opt-exec-ST-4b216e2ffc40/bin/system_tests/main-process: line 213: syntax error near unexpected token `<'

Closes #104 (closed).