Revert: Implement pg_wal_replay_wait() stored procedure

This commit reverts 06c418e163, e37662f221, bf1e650806, 25f42429e2,
ee79928441, and 74eaf66f98 per review by Heikki Linnakangas.

Discussion: https://postgr.es/m/b155606b-e744-4218-bda5-29379779da1a%40iki.fi

src/backend/access/transam/xact.c

@@ -38,7 +38,6 @@
 #include "commands/async.h"
 #include "commands/tablecmds.h"
 #include "commands/trigger.h"
-#include "commands/waitlsn.h"
 #include "common/pg_prng.h"
 #include "executor/spi.h"
 #include "libpq/be-fsstubs.h"
@@ -2772,11 +2771,6 @@ AbortTransaction(void)
 	 */
 	LWLockReleaseAll();
 
-	/*
-	 * Cleanup waiting for LSN if any.
-	 */
-	WaitLSNCleanup();
-
 	/* Clear wait information and command progress indicator */
 	pgstat_report_wait_end();
 	pgstat_progress_end_command();

src/backend/access/transam/xlog.c

@@ -66,7 +66,6 @@
 #include "catalog/catversion.h"
 #include "catalog/pg_control.h"
 #include "catalog/pg_database.h"
-#include "commands/waitlsn.h"
 #include "common/controldata_utils.h"
 #include "common/file_utils.h"
 #include "executor/instrument.h"
@@ -6130,12 +6129,6 @@ StartupXLOG(void)
 	UpdateControlFile();
 	LWLockRelease(ControlFileLock);
 
-	/*
-	 * Wake up all waiters for replay LSN.  They need to report an error that
-	 * recovery was ended before achieving the target LSN.
-	 */
-	WaitLSNSetLatches(InvalidXLogRecPtr);
-
 	/*
 	 * Shutdown the recovery environment.  This must occur after
 	 * RecoverPreparedTransactions() (see notes in lock_twophase_recover())

src/backend/access/transam/xlogrecovery.c

@@ -43,7 +43,6 @@
 #include "backup/basebackup.h"
 #include "catalog/pg_control.h"
 #include "commands/tablespace.h"
-#include "commands/waitlsn.h"
 #include "common/file_utils.h"
 #include "miscadmin.h"
 #include "pgstat.h"
@@ -1829,16 +1828,6 @@ PerformWalRecovery(void)
 				break;
 			}
 
-			/*
-			 * If we replayed an LSN that someone was waiting for then walk
-			 * over the shared memory array and set latches to notify the
-			 * waiters.
-			 */
-			if (waitLSN &&
-				(XLogRecoveryCtl->lastReplayedEndRecPtr >=
-				 pg_atomic_read_u64(&waitLSN->minWaitedLSN)))
-				WaitLSNSetLatches(XLogRecoveryCtl->lastReplayedEndRecPtr);
-
 			/* Else, try to fetch the next WAL record */
 			record = ReadRecord(xlogprefetcher, LOG, false, replayTLI);
 		} while (record != NULL);