Use `getDefaultCliVersion` for `start-proxy` #7044

Job	Run time
Ruby analysis (ubuntu-latest, linked)	49s
Ruby analysis (ubuntu-latest, default)	52s
Ruby analysis (macos-latest, linked)	57s
Ruby analysis (macos-latest, default)	1m 6s
Ruby analysis (macos-latest, nightly-latest)	1m 10s
Ruby analysis (ubuntu-latest, nightly-latest)	51s
	5m 45s

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