Fix merge issue

Author: fvictorio

v-next/hardhat/src/internal/builtin-plugins/solidity/build-system/build-system.ts

@@ -297,8 +297,6 @@ export class SolidityBuildSystemImplementation implements SolidityBuildSystem {
     rootFilePaths: string[],
     options?: GetCompilationJobsOptions,
   ): Promise<CompilationJobCreationError | GetCompilationJobsResult> {
-    const isolated = options?.isolated ?? false;
-
     await this.#downloadConfiguredCompilers(options?.quiet);
 
     const dependencyGraph = await buildDependencyGraph(