refactor(solana): remove dummy ws connection in SolanaClient

[swimthor]

It passes the qa full test in https://exsphere.slack.com/archives/C02PVCS2PKQ/p1665410870060659?thread_ts=1665393074.911999&cid=C02PVCS2PKQ

To be honest I didn't see any actual code change in @solana/web3.js since #284 (comment). But I am align with Andrew this dummy ws is not needed because when we need the onSignature ws, it will create a new ws connection via https://github.com/solana-labs/solana-web3.js/blob/master/src/connection.ts#L5025-L5028

Notion ticket: https://www.notion.so/exsphere/Investigate-whether-we-still-need-a-dummy-websocket-connection-in-SolanaConnection-018975be2b1749a3b636644a07e2e5b9

Checklist

• Github project and label have been assigned
• Tests have been added or are unnecessary
• Docs have been updated or are unnecessary
• Preview deployment works (visit the Cloudflare preview URL)
• Manual testing in #product-testing completed or unnecessary
• New i18n strings do not contain any security vulnerabilities (e.g. should not allow translator to update email/url)
• When fetching new translations from external sources, do a sanity check (e.g. get people who speak the language to check, shove all new translations into Google translate)

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[wormat]

OK let's give this another go but ask the testers to try again on swim.io once it's merged.