Reorder actions in ProcArrayApplyRecoveryInfo()

Reorder actions in ProcArrayApplyRecoveryInfo()

Since 5a1dfde8334b, 2PC filenames use FullTransactionId.  Thus, it needs to
convert TransactionId to FullTransactionId in StandbyTransactionIdIsPrepared()
using TransamVariables->nextXid.  However, ProcArrayApplyRecoveryInfo()
first releases locks with usage StandbyTransactionIdIsPrepared(), then advances
TransamVariables->nextXid.  This sequence of actions could cause errors.
This commit makes ProcArrayApplyRecoveryInfo() advance
TransamVariables->nextXid before releasing locks.

Reported-by: Thomas Munro, Michael Paquier
Discussion: https://postgr.es/m/CA%2BhUKGLj_ve1_pNAnxwYU9rDcv7GOhsYXJt7jMKSA%3D5-6ss-Cw%40mail.gmail.com
Discussion: https://postgr.es/m/Zadp9f4E1MYvMJqe%40paquier.xyz