Fix incompatible 'measurement' state and 'volume' device class warnings in Overkiz

[pdecat]

This PR includes fixes to eliminate warning such as:

2023-12-02 09:20:39.475 INFO (MainThread) [homeassistant.components.water_heater] Setting up water_heater.overkiz
2023-12-02 09:20:39.482 WARNING (MainThread) [homeassistant.components.sensor] Entity sensor.dhwp_actuator_water_volume_estimation_at_40_degc (<class 'homeassistant.components.overkiz.sensor.OverkizStateSensor'>) is using state class 'measurement' which is impossible considering device class ('volume') it is using; expected None or one of 'total', 'total_increasing'; Please update your configuration if your entity is manually configured, otherwise create a bug report at https://github.com/home-assistant/core/issues?q=is%3Aopen+is%3Aissue+label%3A%22integration%3A+overkiz%22
2023-12-02 09:20:39.483 WARNING (MainThread) [homeassistant.components.sensor] Entity sensor.dhwp_actuator_water_consumption (<class 'homeassistant.components.overkiz.sensor.OverkizStateSensor'>) is using state class 'measurement' which is impossible considering device class ('volume') it is using; expected None or one of 'total', 'total_increasing'; Please update your configuration if your entity is manually configured, otherwise create a bug report at https://github.com/home-assistant/core/issues?q=is%3Aopen+is%3Aissue+label%3A%22integration%3A+overkiz%22

Such changes were already mentioned in several PRs, but never made it into dev:

• Add Water device class to Overkiz #87139 (review)
• Fix Overkiz wrong measurement warning #89948

[home-assistant]

Hey there @iMicknl, @vlebourl, @tetienne, @nyroDev, mind taking a look at this pull request as it has been labeled with an integration (overkiz) you are listed as a code owner for? Thanks!

Code owner commands

Code owners of overkiz can trigger bot actions by commenting:

• @home-assistant close Closes the pull request.
• @home-assistant rename Awesome new title Renames the pull request.
• @home-assistant reopen Reopen the pull request.
• @home-assistant unassign overkiz Removes the current integration label and assignees on the pull request, add the integration domain after the command.
• @home-assistant add-label needs-more-information Add a label (needs-more-information, problem in dependency, problem in custom component) to the pull request.
• @home-assistant remove-label needs-more-information Remove a label (needs-more-information, problem in dependency, problem in custom component) on the pull request.

[tetienne]

Thx 🙏 and indeed I never merged my PR

[iMicknl]

LGTM! Thanks, @pdecat.

This change was long due indeed..