When more than 10 integration tests are scheduled (or any change that
triggers run_all, e.g. core/infra changes that would run all 117 files),
fan out the pytest job into 3 parallel matrix entries. Below the
threshold, a single bucket runs as before, so small targeted PRs see no
extra job overhead.
determine-jobs.py now owns the bucketing end-to-end: it expands run_all
into the explicit glob of tests/integration/test_*.py and pre-splits the
sorted list using the same balanced contiguous-partition formula as
script/clang-tidy. The CI workflow consumes the precomputed buckets via
fromJson() in the matrix, mirroring how component-test-batches works,
so no shell-side splitting is needed.
The previous integration-tests-run-all and integration-test-files
workflow outputs are replaced by a single integration-test-buckets
list-of-objects ({name, tests}); the integration-tests gate boolean is
unchanged.
c3ebc39262