Impossible to increase maxFrameSize for coraza-spoa

[L10nf1sh]

Refers to issue corazawaf/coraza-spoa#194

[fionera]

This is not as easy sadly. Currently all connections are allowed to share the same framebuffer pool. This would break as soon as it is allowed to increase the size. This would either require a config var to increase it forcefully or have separate pools per connection.