MDEV-31362 recv_sys_t::apply(bool): Assertion `!last_batch || recovered_lsn == scanned_lsn' failed

recv_sys_t::apply(): Remove a bogus debug assertion that had been
added in commit f2c17cc9 (MDEV-29911).

It is perfectly normal that when the server was killed in the middle of
writing multiple redo log blocks, the recovery would end such that
recv_sys.scanned_lsn will point to the end of the last complete 512-byte
log block, but recv_sys.recovered_lsn will be less than that.

Also, correct the function comment of recv_sys_t::parse().

storage/innobase/include/log0recv.h

@@ -394,7 +394,7 @@ struct recv_sys_t
   bool add(map::iterator it, lsn_t start_lsn, lsn_t lsn,
            const byte *l, size_t len);
 
-  /** Parse and register one mini-transaction in log_t::FORMAT_10_5.
+  /** Parse and register mini-transactions in log_t::FORMAT_10_5.
   @param checkpoint_lsn  the log sequence number of the latest checkpoint
   @param store           whether to store the records
   @param apply           whether to apply file-level log records

storage/innobase/log/log0recv.cc

@@ -2396,7 +2396,7 @@ void recv_sys_t::rewind(const byte *end, const byte *begin) noexcept
   pages_it= pages.end();
 }
 
-/** Parse and register one mini-transaction in log_t::FORMAT_10_5.
+/** Parse and register mini-transactions in log_t::FORMAT_10_5.
 @param checkpoint_lsn  the log sequence number of the latest checkpoint
 @param store           whether to store the records
 @param apply           whether to apply file-level log records
@@ -2404,7 +2404,7 @@ void recv_sys_t::rewind(const byte *end, const byte *begin) noexcept
 or corruption was noticed */
 bool recv_sys_t::parse(lsn_t checkpoint_lsn, store_t *store, bool apply)
 {
- restart:
+restart:
   mysql_mutex_assert_owner(&log_sys.mutex);
   mysql_mutex_assert_owner(&mutex);
   ut_ad(parse_start_lsn);
@@ -3626,7 +3626,6 @@ void recv_sys_t::apply(bool last_batch)
     recv_no_ibuf_operations = !last_batch ||
       srv_operation == SRV_OPERATION_RESTORE ||
       srv_operation == SRV_OPERATION_RESTORE_EXPORT;
-    ut_ad(!last_batch || recovered_lsn == scanned_lsn);
     progress_time= time(nullptr);
     report_progress();