CP-50836: Add VM_migrate_downtime and request_shutdown spans to help … #4277

Job	Run time
Python tests (3.11)	3m 32s
Deprecation tests	8s
Test SDK builds / Generate SDK sources	4m 14s
Finish coverage upload	6s
Test SDK builds / Build C SDK	17s
Test SDK builds / Build Java SDK	37s
Test SDK builds / Build C# SDK	1m 59s
Test SDK builds / Build PowerShell 5.x SDK (.NET Framework 4.5)	2m 40s
Test SDK builds / Build PowerShell 7.x SDK (6)	1m 56s
Test SDK builds / Build PowerShell 7.x SDK (8)	1m 57s
	17m 26s

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