feat(sdk-coin-polyx): replace placeholder v8 testnet metadata with live RPC #3551

Job	Run time
Generate head API spec	6m 56s
Generate merge base API spec	7m 20s
Check specs identical	5s
API Spec Check	3s
Generate vacuum reports for API spec	-1s
Check breaking changes	-1s
Linter Override	0s
	14m 22s

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