WL#8403: MTR should initialize DB using mysqld --initialize option

MTR needs incorporate --initialize and deprecate --bootstrap.

1. Introduce --initilazie, --initilaize-insecure.
   For the time being initialize-insecure is to be implemented for its 
simplicity in implementation. --initialize needs to be implemented in future and 
not to be missed.

2. Proper handiling of database test.
   Current implementation of "test" database in MTR is a schema, but that needs 
to be converted to a proper database.

3. Handling changes in test case.
   Several test cases fails due to changes in "test" databse which needs to 
modified.


Althoug currently --bootstrap and --initiliaze is supported in MySQLD, MTR 
cannot support both in its current form as result file cahnge due to adaptation 
of --initialize.

R1 : The database "test" needs to be created during the initialize process with 
proper grants.
R2: The $MYSQL_BOOTSTRAP_CMD used for starting of server in the test need not 
include the path to datadir, as some test may create new datadir in its process.
R3: The datadir to be used should be empty and should be copied while processing 
--parallel.
R4: MTR needs to get rid of --bootstrap option as --bootstrap --initialize can 
not be used simultaneously.
R5: Test modifications required due to cahnge in "test" database .
R6: Modification in other databases created in the tests may be required.
R7: Modification in the way .sql files passed during bootstrap/initialize 
process.