opening_hours and collection_times quests use different time-picker (12h am/pm vs. 24h)

[mnalis]

opening hours quests shows time picker with 12hour am/pm, while postbox collection times quest shows android time picker with 24hour variant. They should probably use same time picker (as decided by OS locale settings).

(Might be related to #2795 and #2799 (comment))

How to Reproduce

• uninstall and install SC again

• unselect all quests except opening hours and postbox collection times quests

• click on opening hours quest, click add opening hours, select weekdays, this dialog appears:
  

• click on postbox collection times quest, click add collection time, select weekdays, this dialog appears:
  

Versions affected

• StreetComplete v31.3 (from f-droid)
• phone: Xiaomi Redmi Note 3 pro
• OS: MIUI 10.2 (Android 6.0.1)