MDEV-32634: wsrep_provider_options can be truncated on deep and long directory paths

This is caused by fact that VARIABLE_VALUE is defined in
variables_fields_info (sql_show.cc) as 2048.
wsrep_provider_options contain few path variables and
this could cause string truncation on deep and long
directory paths.

Signed-off-by: Julius Goryavsky <julius.goryavsky@mariadb.com>

Author: janlindstrom

mysql-test/main/show_check.result

@@ -103,19 +103,19 @@ drop table t1;
 show variables like "wait_timeout%";
 Catalog	Database	Table	Table_alias	Column	Column_alias	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
 def	information_schema	SESSION_VARIABLES	SESSION_VARIABLES	VARIABLE_NAME	Variable_name	253	64	12	N	4097	0	8
-def	information_schema	SESSION_VARIABLES	SESSION_VARIABLES	VARIABLE_VALUE	Value	253	2048	5	N	4097	0	8
+def	information_schema	SESSION_VARIABLES	SESSION_VARIABLES	VARIABLE_VALUE	Value	253	4096	5	N	4097	0	8
 Variable_name	Value
 wait_timeout	28800
 show variables like "WAIT_timeout%";
 Catalog	Database	Table	Table_alias	Column	Column_alias	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
 def	information_schema	SESSION_VARIABLES	SESSION_VARIABLES	VARIABLE_NAME	Variable_name	253	64	12	N	4097	0	8
-def	information_schema	SESSION_VARIABLES	SESSION_VARIABLES	VARIABLE_VALUE	Value	253	2048	5	N	4097	0	8
+def	information_schema	SESSION_VARIABLES	SESSION_VARIABLES	VARIABLE_VALUE	Value	253	4096	5	N	4097	0	8
 Variable_name	Value
 wait_timeout	28800
 show variables like "this_doesn't_exists%";
 Catalog	Database	Table	Table_alias	Column	Column_alias	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr
 def	information_schema	SESSION_VARIABLES	SESSION_VARIABLES	VARIABLE_NAME	Variable_name	253	64	0	N	4097	0	8
-def	information_schema	SESSION_VARIABLES	SESSION_VARIABLES	VARIABLE_VALUE	Value	253	2048	0	N	4097	0	8
+def	information_schema	SESSION_VARIABLES	SESSION_VARIABLES	VARIABLE_VALUE	Value	253	4096	0	N	4097	0	8
 Variable_name	Value
 show table status from test like "this_doesn't_exists%";
 Catalog	Database	Table	Table_alias	Column	Column_alias	Type	Length	Max length	Is_null	Flags	Decimals	Charsetnr

sql/sql_show.cc

@@ -9876,7 +9876,7 @@ ST_FIELD_INFO variables_fields_info[]=
 {
   {"VARIABLE_NAME", 64, MYSQL_TYPE_STRING, 0, 0, "Variable_name",
    SKIP_OPEN_TABLE},
-  {"VARIABLE_VALUE", 2048, MYSQL_TYPE_STRING, 0, 0, "Value", SKIP_OPEN_TABLE},
+  {"VARIABLE_VALUE", 4096, MYSQL_TYPE_STRING, 0, 0, "Value", SKIP_OPEN_TABLE},
   {0, 0, MYSQL_TYPE_STRING, 0, 0, 0, SKIP_OPEN_TABLE}
 };