Description
Enable the buffer pool to adjust innodb_buffer_pool_size based on available RAM, targeting 75-80% by default, with configurable scaling factors and limits for stability. See https://jira.mariadb.org/browse/MDEV-36194 for more information on use case.

Tasks

1. Implement periodic RAM detection (e.g., via syscalls or OS notifications).
   Add system variables:
2. buffer_pool_auto_scale_method= {OFF, RAM_percentage}

   (default: OFF).

3. buffer_pool_auto_scale_factor=N (default: 0.75, range: 0.1–1.0).
4. buffer_pool_min_size (default: 128MB), buffer_pool_max_size (default: unlimited).
5. Set innodb_buffer_pool_size = RAM * buffer_pool_auto_scale_factor, respecting limits.
6. Reject manual SET GLOBAL innodb_buffer_pool_size when auto-scaling is active.
7. Make polling frequency configurable (e.g., once per second, per minute), defaulting to once per minute.

Acceptance Criteria

1. buffer_pool_auto_scale_method=RAM_percentage activates RAM-based scaling.
2. Example: 16GB RAM, buffer_pool_auto_scale_factor=0.75, innodb_buffer_pool_size=12GB.
3. buffer_pool_auto_scale_factor configurable between 0.1–1.0.
4. Respects buffer_pool_min_size and buffer_pool_max_size.
5. Manual SET GLOBAL innodb_buffer_pool_size fails with an error.
6. Ensure the system variables are manually configurable.