shim/runtime/config: Fix return value error in the GetEnv function

Signed-off-by: NYilin Li <YiLin.Li@linux.alibaba.com>

shim/runtime/config/config.go

@@ -81,7 +81,7 @@ func GetEnv(spec *specs.Spec, key string) (string, bool) {
 		}
 		return p[1], true
 	}
-	return "", true
+	return "", false
 }
 
 func UpdateEnclaveEnvConfig(cPath string) error {