drop legacy testnet support

[harryEth]

📦 Pull Request

[Provide a general summary of the pull request here.]

✅ Fixed Issues

• [List any fixed issues here like: Fixes #XXXX]

🚨 Test instructions

[Describe any additional context required to test the PR/feature/bug fix.]

⚠️ Don't forget to add a semver label!

• patch: Bug Fix?
• minor: New Feature?
• major: Breaking Change?
• skip-release: It's unnecessary to publish this change.

[shortcut-integration]

This pull request has been linked to Shortcut Story #61855: M4: Magic SDK major release.

[magiclabsFE]

🚀 PR was released in @magic-ext/algorand@5.0.0, @magic-ext/avalanche@5.0.0, @magic-ext/bitcoin@5.0.0, @magic-ext/conflux@3.0.0, @magic-ext/connect@3.0.0, @magic-ext/cosmos@5.0.0, @magic-ext/ed25519@1.0.0, @magic-ext/flow@5.0.0, @magic-ext/harmony@5.0.0, @magic-ext/icon@5.0.0, @magic-ext/near@5.0.0, @magic-ext/oauth@4.0.0, @magic-ext/polkadot@5.0.0, @magic-ext/react-native-oauth@4.0.0, @magic-ext/solana@6.0.0, @magic-ext/taquito@2.0.0, @magic-ext/terra@2.0.0, @magic-ext/tezos@5.0.0, @magic-ext/webauthn@4.0.0, @magic-ext/zilliqa@5.0.0, @magic-sdk/commons@6.0.0, @magic-sdk/pnp@4.0.0, @magic-sdk/provider@10.0.0, @magic-sdk/react-native@11.0.0, @magic-sdk/types@9.0.0, magic-sdk@10.0.0 🚀