MDEV-22650 Dirty compressed page checksum validation fails

Problem:
=======
  While evicting the uncompressed page from buffer pool, InnoDB writes
the checksum for the compressed page in buf_LRU_free_page().
So while flushing the compressed page, checksum validation fails
when innodb_checksum_algorithm variable changed to strict_none.

Solution:
========
- Calculate the checksum only during flushing of page. Removed the
checksum write in buf_LRU_free_page().

storage/innobase/buf/buf0buf.cc

@@ -4625,7 +4625,7 @@ buf_page_get_low(
 		buf_pool->mutex or block->mutex. */
 
 		{
-			bool	success = buf_zip_decompress(block, TRUE);
+			bool	success = buf_zip_decompress(block, false);
 
 			if (!success) {
 				buf_pool_mutex_enter(buf_pool);

storage/innobase/buf/buf0flu.cc

@@ -1069,10 +1069,8 @@ buf_flush_write_block_low(
 	case BUF_BLOCK_ZIP_DIRTY:
 		frame = bpage->zip.data;
 
-		mach_write_to_8(frame + FIL_PAGE_LSN,
-				bpage->newest_modification);
-
-		ut_a(page_zip_verify_checksum(frame, bpage->size.physical()));
+		buf_flush_update_zip_checksum(frame, bpage->size.physical(),
+					      bpage->newest_modification);
 		break;
 	case BUF_BLOCK_FILE_PAGE:
 		frame = bpage->zip.data;

storage/innobase/buf/buf0lru.cc

@@ -1617,27 +1617,6 @@ buf_LRU_free_page(
 	UNIV_MEM_INVALID(((buf_block_t*) bpage)->frame,
 			 UNIV_PAGE_SIZE);
 
-	if (b != NULL) {
-
-		/* Compute and stamp the compressed page
-		checksum while not holding any mutex.  The
-		block is already half-freed
-		(BUF_BLOCK_REMOVE_HASH) and removed from
-		buf_pool->page_hash, thus inaccessible by any
-		other thread. */
-
-		ut_ad(b->size.is_compressed());
-
-		const uint32_t	checksum = page_zip_calc_checksum(
-			b->zip.data,
-			b->size.physical(),
-			static_cast<srv_checksum_algorithm_t>(
-				srv_checksum_algorithm));
-
-		mach_write_to_4(b->zip.data + FIL_PAGE_SPACE_OR_CHKSUM,
-				checksum);
-	}
-
 	buf_pool_mutex_enter(buf_pool);
 
 	if (b != NULL) {