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.result

@@ -15,6 +15,10 @@ The following specify which files/extra groups are read (specified before remain
  --alter-algorithm[=name] 
  Specify the alter table algorithm. One of: DEFAULT, COPY,
  INPLACE, NOCOPY, INSTANT
+ --analyze-max-length=# 
+ Fields that require more storage than analyze_max_length
+ and are not listed in ANALYZE ... FOR COLUMNS () will
+ automatically be skipped by ANALYZE TABLE PERSISTENT
  --analyze-sample-percentage=# 
  Percentage of rows from the table ANALYZE TABLE will
  sample to collect table statistics. Set to 0 to let