soroban-cli: Only Give RC SDK Contract Compilation Warning/Errors if Using Pubnet #3059

Job	Run time
Integration tests (ubuntu-20.04, 1.21, .CLI.)	19m 10s
Build (ubuntu-latest, x86_64-unknown-linux-gnu, amd64)	2m 30s
Unit tests (ubuntu-20.04, 1.21)	6m 41s
Integration tests (ubuntu-20.04, 1.21, ^Test(([^C])\|(C[^L])\|(CL[^I])).*$)	16m 18s
Build (ubuntu-latest, aarch64-unknown-linux-gnu, arm64)	3m 3s
Build (macos-latest, x86_64-apple-darwin, amd64)	5m 0s
Build (macos-latest, aarch64-apple-darwin, arm64)	5m 5s
Build (windows-latest, x86_64-pc-windows-gnu, amd64)	6m 27s
	1h 4m 14s

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