Move standard_tracer's subscription observer to cpp #808

Job	Run time
Unit tests (ubuntu-latest, 3.10, 5, pyqt)	3m 27s
Unit tests (ubuntu-latest, 3.10, 6, pyqt)	3m 0s
Unit tests (ubuntu-latest, 3.11, 6, pyqt)	2m 34s
Unit tests (ubuntu-latest, 3.12, 6, pyqt)	3m 22s
Unit tests (ubuntu-latest, 3.13, 6, pyqt)	3m 35s
Unit tests (windows-latest, 3.10, 5, pyqt)	4m 56s
Unit tests (windows-latest, 3.10, 6, pyqt)	4m 57s
Unit tests (windows-latest, 3.10, 6, pyside)	4m 4s
Unit tests (windows-latest, 3.11, 6, pyqt)	3m 47s
Unit tests (windows-latest, 3.11, 6, pyside)	4m 2s
Unit tests (windows-latest, 3.12, 6, pyqt)	4m 35s
Unit tests (windows-latest, 3.13, 6, pyqt)	4m 36s
Unit tests (macos-latest, 3.10, 5, pyqt)	2m 38s
Unit tests (macos-latest, 3.10, 6, pyqt)	3m 15s
Unit tests (macos-latest, 3.10, 6, pyside)	2m 46s
Unit tests (macos-latest, 3.11, 6, pyqt)	2m 14s
Unit tests (macos-latest, 3.11, 6, pyside)	2m 25s
Unit tests (macos-latest, 3.12, 6, pyqt)	2m 22s
Unit tests (macos-latest, 3.13, 6, pyqt)	2m 8s
	1h 4m 43s

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