tm: safety check for cases when xavps for serial forking fail to be added to root list

- in error cases remove xavp group from the root list instead of local destroy, otherwise it
  stays linked in root list and can cause invalid memory access
- discovered on investigating memory leak issue reported by Geoffrey M.

(cherry picked from commit 4f95cfa6266bd66a1516629ed3445d98da433b2b)