cli: Fix excessive test validator requests

[acheroncrypto]

Problem

Anchor sends thousands of network requests in order to decide whether the test validator is initialized. Even though this is only for localnet, the amount of network requests is unnecessary.

Summary of changes

• Check whether the test validator is initialized every 100ms (instead of 1ms)
• Remove usage of unwrap in test_validator_file_paths function, propagate errors instead

[vercel]

@acheroncrypto is attempting to deploy a commit to the coral-xyz Team on Vercel.

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