[16.0][FIX]hr_holidays_public: handle incompatibility with `hr_work_entry_holidays` by propagating the context upwards

[PicchiSeba]

The method _get_number_of_days introduced in hr_work_entry_holidays, is not being passed exclude_public_holidays in the context. With this PR we propagate it in the calling methods too.

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[aleuffre]

Hello @OCA/human-resources-maintainers , admittedly this is something of a hack but we've been using it in production for a couple of months now, and it works. Could you take a look?