Fix issues when running multiple overlap removal configurations in CP algorithms

Currently, if a user tries to run multiple overlap removal blocks with different configuration, neither selectionName nor postfix is propagated to the output variables that specify the selection. This MR fixes this bug and also cleans up the interface a bit:

• postfix option is removed as it is confusing having both this and selectionName
• internally, all decorations and output variables are appended a postfix based on the selectionName

Importantly, for people using single OR configuration with default settings (i.e. not setting selectionName/postfix manually), nothing changes.