Solana: multinode-demo/validator.sh: Remove IP address hard code

[mvines]

This has already bite us once: 9688f8fb64c33b3ad34632ce7a4e6eb92915f674

In the short term we can just use dig to resolve the DNS name instead. One small catch, need to confirm dig is available from the Snap environment and if not probably ship a copy of it (example: https://github.com/solana-labs/solana/commit/f0446c7e88198ebd2e219824192e20512ea96df1#diff-5fde7a6d86053f0e1d88c0a2a238941f)

[blackwatertepes]

This issue has already been addressed: https://github.com/solana-labs/solana/blob/master/multinode-demo/common.sh#L189

[mvines]

Almost, we still have this line: https://github.com/solana-labs/solana/blob/e2e569cb43c7a0db9203b7554f369c984f7389de/multinode-demo/common.sh#L177

I'm actually right in this code now so I can quickly do this too