Tidy up rmgen point location randomization and retry loops.

Remove retryPlacing args helperobject by making use of the hoisting effect.
Remove the deprecation warning in retryPlacing and equally and the unused behaveDeprecated argument from createAreas and createAreasInAreas, refs #4294, rP19929, D249.

Rename randomizePlacerCoordinates to randomizeCoordinates and placer to group in the four createObjectGroups functions following rP17728,
because Groups aren't Placers (as established in rP20355), just share the randomizable x/z properties.

Fix randomizeCoordinates on square maps offering entity locations outside of the passable map area that are only rejected later in the codeflow, missed first in rP14183, but also rP18450 and rP20283, refs #4012, #4814.
Clarify randomizeCoordinates by passing a boolean stating whether to include the impassable map border instead of a varying halfMapSize.
Remove the unused halfMapSize argument from the randomizePlacerCoordinatesFromAreas call in createAreasInAreas.