Resolve task process variable

Fixes #103018

src/vs/workbench/contrib/tasks/browser/terminalTaskSystem.ts

@@ -1022,7 +1022,7 @@ export class TerminalTaskSystem implements ITaskSystem {
 		} else {
 			let commandExecutable = (task.command.runtime !== RuntimeType.CustomExecution) ? CommandString.value(command) : undefined;
 			let executable = !isShellCommand
-				? this.resolveVariable(variableResolver, '${' + TerminalTaskSystem.ProcessVarName + '}')
+				? this.resolveVariable(variableResolver, this.resolveVariable(variableResolver, '${' + TerminalTaskSystem.ProcessVarName + '}'))
 				: commandExecutable;
 
 			// When we have a process task there is no need to quote arguments. So we go ahead and take the string value.