fix(terraform): try/catch HCL parsing (#19792)

lib/modules/manager/terraform/hcl/index.ts

 import * as hcl_parser from 'hcl2-parser';
 
 export function parseHCL(content: string): any {
-  return hcl_parser.parseToObject(content)[0];
+  try {
+    return hcl_parser.parseToObject(content)[0];
+  } catch (err) /* istanbul ignore next */ {
+    return null;
+  }
 }
 
 export function parseJSON(content: string): any {