[RM] make task_manager::m_tdag a reference #4649

Job	Run time
find-duplicate-workflows	8s
clang-tidy	0s
read-build-matrix	8s
build-and-test (dpcpp, ad494e9d, false, 22.04, intel, Debug)	2m 25s
build-and-test (dpcpp, ad494e9d, false, 22.04, intel, Release)	2m 25s
build-and-test (dpcpp, latest, true, 24.04, intel, Debug)	2m 24s
build-and-test (dpcpp, latest, true, 24.04, intel, Release)	2m 24s
build-and-test (acpp, v24.06.0, false, 22.04, nvidia, Debug)	2m 28s
build-and-test (acpp, v24.06.0, false, 22.04, nvidia, Release)	2m 28s
build-and-test (acpp, latest, true, 24.04, nvidia, Debug)	2m 28s
build-and-test (acpp, latest, true, 24.04, nvidia, Release)	2m 28s
build-and-test (simsycl, HEAD, true, 24.04, intel, Release)	2m 22s
build-and-test (simsycl, HEAD, true, 24.04, intel, Debug)	2m 22s
tag-latest-containers	1s
report	1s
	24m 32s

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