solana: define __dirname in ESM anchor tests

multi_instance.test.ts and upgrade_authority_decoupling.test.ts used the
CommonJS __dirname global, which is undefined under jest's ESM mode, so
both suites failed to load with ReferenceError. This was masked while the
SDK build (Setup SDK step) was failing earlier in the job. Derive it from
import.meta.url, mirroring anchor.test.ts.

Author: kcsongor

solana/tests/anchor/multi_instance.test.ts

@@ -30,10 +30,13 @@ import {
 } from "../../ts/sdk/index.js";
 import { NTT } from "../../ts/index.js";
 import { TestHelper, TestMint, assert, signSendWait } from "./utils/helpers.js";
+import { fileURLToPath } from "url";
 
 registerDefinitionsNtt();
 registerSolanaNtt();
 
+// Native ESM (jest useESM) has no __dirname; derive it from import.meta.url.
+const __dirname = fileURLToPath(new URL(".", import.meta.url));
 const SOLANA_ROOT_DIR = `${__dirname}/../../`;
 const VERSION: IdlVersion = "4.0.0";
 const TOKEN_PROGRAM = spl.TOKEN_2022_PROGRAM_ID;

solana/tests/anchor/upgrade_authority_decoupling.test.ts

@@ -26,10 +26,13 @@ import {
   BPF_LOADER_UPGRADEABLE_PROGRAM_ID,
   programDataAddress,
 } from "../../ts/lib/utils.js";
+import { fileURLToPath } from "url";
 
 registerDefinitionsNtt();
 registerSolanaNtt();
 
+// Native ESM (jest useESM) has no __dirname; derive it from import.meta.url.
+const __dirname = fileURLToPath(new URL(".", import.meta.url));
 const SOLANA_ROOT_DIR = `${__dirname}/../../`;
 const VERSION: IdlVersion = "4.0.0";
 const TOKEN_PROGRAM = spl.TOKEN_2022_PROGRAM_ID;