fix: measure individual call durations in sequential phase of concurrency decorator #303

Job	Run time
check-linked-issue	4s
determine-changes / detect	11s
type-check	25s
unit-tests (ubuntu-latest, 3.9)	8m 55s
coverage	7m 19s
prek / prek	30s
unit-tests (ubuntu-latest, 3.10)	7m 56s
unit-tests (windows-latest, 3.13)	11m 49s
unit-tests (ubuntu-latest, 3.12)	7m 43s
unit-tests (ubuntu-latest, 3.13)	7m 58s
unit-tests (ubuntu-latest, 3.14)	6m 15s
e2e-python (coverage-e2e, end_to_end_test_coverage.py, black)	5m 5s
e2e-python (topological-sort, end_to_end_test_topological_sort_worktree.py, 5)	2m 26s
e2e-python (bubble-sort-unittest, end_to_end_test_bubblesort_unittest.py, 40)	9m 30s
e2e-python (bubble-sort-pytest-nogit, end_to_end_test_bubblesort_pytest.py, 70, true)	6m 10s
e2e-python (init-optimization, end_to_end_test_init_optimization.py, 10)	3m 13s
e2e-python (benchmark-bubble-sort, end_to_end_test_benchmark_sort.py, 5)	4m 46s
e2e-python (async-optimization, end_to_end_test_async.py, 10)	2m 36s
e2e-python (futurehouse-structure, end_to_end_test_futurehouse.py, 5)	2m 32s
unit-tests (ubuntu-latest, 3.11)	7m 16s
e2e-python (tracer-replay, end_to_end_test_tracer_replay.py, 10)	5m 41s
e2e-java	0s
e2e-js	0s
required checks passed	5s
	1h 48m 25s

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