data: fix Japan vaccinaion aggregation method (1st, 2nd vaccinated)

[lisphilar]

Related issues

#1373

What was changed

Japan vaccination data: fixed aggregation method.
The primary source provides

• $[V_{1st}(t) - V_{1st}(t-1)]$, $[V_{1st}(t+1) - V_{1st}(t)]$,...
• $[V_{2nd}(t) - V_{2nd}(t-1)]$, $[V_{2nd}(t+1) - V_{2nd}(t)]$,...
• $V_{3rd}(t)$, $V_{3rd}(t+1)$,...

The current files of this repository provided the followings mistakenly:

• $[V_{1st}(t) - V_{1st}(t-1)]$, $[V_{1st}(t+1) - V_{1st}(t)]$,...
• $[V_{2nd}(t) - V_{2nd}(t-1)]$, $[V_{2nd}(t+1) - V_{2nd}(t)]$,...
• $V_{3rd}(t)$, $V_{3rd}(t+1)$,...

After merging this pull request,

• $V_{1st}(t)$, $V_{1st}(t+1)$,...
• $V_{2nd}(t)$, $V_{2nd}(t+1)$,...
• $V_{3rd}(t)$, $V_{3rd}(t+1)$,...