MDEV-36536 Add option to not collect statistics for long char/varchars

This is needed to make it easy for users to automatically ignore long
char and varchars when using  ANALYZE TABLE PERSISTENT.
These fields can cause problems as they will consume
'CHARACTERS * MAX_CHARACTER_LENGTH * 2 * number_of_rows' space on disk
during analyze, which can easily be much bigger than the analyzed table.

This commit adds a new user variable, analyze_max_length, default value 4G.
Any field that is bigger than this in bytes, will be ignored by
ANALYZE TABLE PERSISTENT unless it is specified in FOR COLUMNS().

While doing this patch, I noticed that we do not skip GEOMETRY columns from
ANALYZE TABLE, like we do with BLOB. This should be fixed when merging
to the 'main' branch. At the same time we should add a resonable default
value for analyze_max_length, probably 1024, like we have for
max_sort_length.

mysql-test/main/mysqld--help.test

@@ -20,14 +20,14 @@ exec $MYSQLD_BOOTSTRAP_CMD --symbolic-links=0 --log-bin=foo --lower-case-table-n
 
 perl;
   # Variables which we don't want to display in the result file since
-  # their paths may vary:
+  # their paths may vary or they may use a default of 4294967295 :
   @skipvars=qw/basedir open-files-limit general-log-file log plugin-dir plugin-maturity
                log-slow-queries pid-file slow-query-log-file log-basename
                datadir slave-load-tmpdir tmpdir socket thread-pool-size
                large-files-support lower-case-file-system system-time-zone
                collation-server character-set-server log-tc-size table-cache
                table-open-cache table-open-cache-instances max-connections
-               server-uid tls-version version.*/;
+               server-uid tls-version version.* analyze-max-length/;
 
   # Plugins which may or may not be there:
   @plugins=qw/innodb archive blackhole federated partition s3