Allow Proxy creation without a set TraceCtx #5483

Job	Run time
pytester (ubuntu-22.04, 3.10, latest, core)	8m 53s
pytester (ubuntu-22.04, 3.10, latest, ops)	30m 37s
pytester (ubuntu-22.04, 3.10, nightly, core)	8m 50s
pytester (ubuntu-22.04, 3.10, nightly, ops)	30m 27s
pytester (macOS-14, 3.10, latest, core)	7m 40s
pytester (macOS-14, 3.10, latest, ops)	26m 14s
pytester (macOS-14, 3.10, nightly, core)	6m 55s
pytester (macOS-14, 3.10, nightly, ops)	25m 13s
pytester (windows-2022, 3.10, latest, core)	19m 58s
pytester (windows-2022, 3.10, nightly, core)	20m 18s
pytester (ubuntu-22.04, 3.11, latest)	15m 46s
pytester (ubuntu-22.04, 3.12, latest)	18m 36s
testing-guardian	1s
	3h 39m 28s

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