Bug #30576 part_supported_sql_func_innodb.test tries to LOAD DATA outside of var dir

Description:
mysqltest: In included file "./suite/parts/inc/partition_supported_sql_funcs.inc": At line 87: query 'load data infile '$MYSQL_TEST_DIR/suite/parts/inc/$infile' into table t4' failed: 1290: The MySQL server is running with the --secure-file-priv option so it cannot execute this statement
(the last lines may be the most important ones)

The test suite runs the server with --secure-file-priv, which doesn't allow LOAD DATA for files outside the mysql-test/var directory.

How to repeat:
Run the parts.part_supported_sql_func_innodb test.

Suggested fix:
Either start the server without --secure-file-priv for this test, or copy the needed data file into the var dir.

ChangeSet isn't showing up in commits list for some reason.  Here it is:

https://intranet.mysql.com/~tsmith/tmp/suite-parts-1.diff

Horst has verified Tim's patch fixes this and the following 
bugs:
- Bug#30316 Some "parts" tests fail because the server uses "--secure-file-priv"
- Bug#30341: Test suite "parts" needs to be adapted to the new rules disallowing many functio
- Bug#30408: Suite "parts" needs bug numbers updated
- Bug#30411: Suite "parts" needs bug numbers updated: ER_UNIQUE_KEY_NEED_ALL_FIELDS_IN_PF
- Bug#30576: part_supported_sql_func_innodb.test tries to LOAD DATA outside of var dir
- Bug#30581 partition_value tests use disallowed CAST() function

Queued to target-5.1.22

Test case changes only, no need to document

Pushed into 5.1.23-beta