Tune mysql and galera backend settings on scale

- Tune MySQL config settings to be more clouds-specific (reads much
  more common, reads:writes rate is 10(100):1)
  * Limit innodb_buffer_pool_size to 10G and set is as 30% of RAM
  * Update innodb_log_file_size as:
    * If mysql ib_logfiles do not match 25% of innodb_buffer_pool_size (max 2G),
      delete them and update innodb_log_file_size in the config appropriately;
    * Otherwise, use existing ib_logfile0 size to re-evaluate the
      innodb_buffer_pool_size config value to match its real size.
  * Reduce innodb_write_io_threads to 2/2 from 2/8
  * Use innodb_flush_log_at_trx_commit=2 for HA (was 1)
  * Raise FD imits to 102400/102400 from 22058/22058,
  * Raise max connections to 3000/4096 from 2048/2048,
  * Raise open tables limits 10000/10000 from 10000/400.
  * Lower wait_timeout to 3600/3600 (1h) from 28800/28800 (8h)
  * Adjust myisam_sort_buffer_size to 64M from 8388608 bytes
  * Adjust key_buffer_size to 64M from 16777216 bytes
- Sync Puppet galera module params for MySQL module as well
Note: doubled values should be treated as simple/HA case
CI retest

Partial blueprint: optimize-db-performance-at-scale
Change-Id: Ie341da55711e70e38116389a54bda3b4357dafe7
Signed-off-by: Bogdan Dobrelya <bdobrelia@mirantis.com>
Merge "Tune mysql and galera backend settings on scale"