MDEV-11838: Innodb-encryption-algorithm default should be != none

Change default to zlib, this has effect only if user has
explicitly requested page compression and then user
naturally expects that pages are really compressed
if they can be compressed.

mysql-test/suite/innodb/r/innodb-page_compression_default.result

+SET GLOBAL innodb_file_format = `Barracuda`;
+SET GLOBAL innodb_file_per_table = ON;
+create table t1 (c1 int not null primary key auto_increment, b char(200)) engine=innodb page_compressed=1;
+insert into t1 values(NULL,'compressed_text_aaaaaaaaabbbbbbbbbbbbbccccccccccccc');
+insert into t1(b) select b from t1;
+insert into t1(b) select b from t1;
+insert into t1(b) select b from t1;
+insert into t1(b) select b from t1;
+insert into t1(b) select b from t1;
+insert into t1(b) select b from t1;
+insert into t1(b) select b from t1;
+insert into t1(b) select b from t1;
+insert into t1(b) select b from t1;
+insert into t1(b) select b from t1;
+insert into t1(b) select b from t1;
+insert into t1(b) select b from t1;
+insert into t1(b) select b from t1;
+# t1 compressed expected NOT FOUND
+NOT FOUND /compressed_text/ in t1.ibd
+drop table t1;

mysql-test/suite/innodb/t/innodb-page_compression_default.test

+--source include/have_innodb.inc
+
+--disable_query_log
+let $innodb_compression_algorithm_orig=`SELECT @@innodb_compression_algorithm`;
+let $innodb_file_format_orig = `SELECT @@innodb_file_format`;
+let $innodb_file_per_table_orig = `SELECT @@innodb_file_per_table`;
+--enable_query_log
+
+--disable_warnings
+SET GLOBAL innodb_file_format = `Barracuda`;
+SET GLOBAL innodb_file_per_table = ON;
+--enable_warnings
+
+create table t1 (c1 int not null primary key auto_increment, b char(200)) engine=innodb page_compressed=1;
+insert into t1 values(NULL,'compressed_text_aaaaaaaaabbbbbbbbbbbbbccccccccccccc');
+insert into t1(b) select b from t1;
+insert into t1(b) select b from t1;
+insert into t1(b) select b from t1;
+insert into t1(b) select b from t1;
+insert into t1(b) select b from t1;
+insert into t1(b) select b from t1;
+insert into t1(b) select b from t1;
+insert into t1(b) select b from t1;
+insert into t1(b) select b from t1;
+insert into t1(b) select b from t1;
+insert into t1(b) select b from t1;
+insert into t1(b) select b from t1;
+insert into t1(b) select b from t1;
+
+let $wait_condition= select variable_value > 0 from information_schema.global_status where variable_name = 'INNODB_NUM_PAGES_PAGE_COMPRESSED';
+--source include/wait_condition.inc
+
+--let $MYSQLD_DATADIR=`select @@datadir`
+--let t1_IBD = $MYSQLD_DATADIR/test/t1.ibd
+--let SEARCH_RANGE = 10000000
+--let SEARCH_PATTERN=compressed_text
+
+--echo # t1 compressed expected NOT FOUND
+-- let SEARCH_FILE=$t1_IBD
+-- source include/search_pattern_in_file.inc
+
+drop table t1;
+
+# reset system
+--disable_query_log
+--disable_warnings
+EVAL SET GLOBAL innodb_compression_algorithm = $innodb_compression_algorithm_orig;
+EVAL SET GLOBAL innodb_file_per_table = $innodb_file_per_table_orig;
+EVAL SET GLOBAL innodb_file_format = $innodb_file_format_orig;
+--enable_warnings
+--enable_query_log

mysql-test/suite/sys_vars/r/sysvars_innodb.result

@@ -497,9 +497,9 @@ READ_ONLY	NO
 COMMAND_LINE_ARGUMENT	REQUIRED
 VARIABLE_NAME	INNODB_COMPRESSION_ALGORITHM
 SESSION_VALUE	NULL
-GLOBAL_VALUE	none
+GLOBAL_VALUE	zlib
 GLOBAL_VALUE_ORIGIN	COMPILE-TIME
-DEFAULT_VALUE	none
+DEFAULT_VALUE	zlib
 VARIABLE_SCOPE	GLOBAL
 VARIABLE_TYPE	ENUM
 VARIABLE_COMMENT	Compression algorithm used on page compression. One of: none, zlib, lz4, lzo, lzma, or bzip2

storage/innobase/handler/ha_innodb.cc

@@ -19774,7 +19774,7 @@ static MYSQL_SYSVAR_ENUM(compression_algorithm, innodb_compression_algorithm,
   /* We use here the largest number of supported compression method to
   enable all those methods that are available. Availability of compression
   method is verified on innodb_compression_algorithm_validate function. */
-  PAGE_UNCOMPRESSED,
+  PAGE_ZLIB_ALGORITHM,
   &page_compression_algorithms_typelib);
 
 static MYSQL_SYSVAR_LONG(mtflush_threads, srv_mtflush_threads,

storage/xtradb/handler/ha_innodb.cc

@@ -21257,7 +21257,7 @@ static MYSQL_SYSVAR_ENUM(compression_algorithm, innodb_compression_algorithm,
   /* We use here the largest number of supported compression method to
   enable all those methods that are available. Availability of compression
   method is verified on innodb_compression_algorithm_validate function. */
-  PAGE_UNCOMPRESSED,
+  PAGE_ZLIB_ALGORITHM,
   &page_compression_algorithms_typelib);
 
 static MYSQL_SYSVAR_LONG(mtflush_threads, srv_mtflush_threads,