Simplified RuptureGetter/2

[micheles]

By saving the rupture records instead of the proxies and using len(records) as weight. Part of #10209. There is no change in performance for EUR:

# before
| operation-duration | counts | mean    | stddev | min    | max     | slowfac |
|--------------------+--------+---------+--------+--------+---------+---------|
| event_based        | 424    | 14.8517 | 37%    | 1.3335 | 30.6265 | 2.0622  |

# after
| operation-duration | counts | mean    | stddev | min    | max     | slowfac |
|--------------------+--------+---------+--------+--------+---------+---------|
| event_based        | 424    | 14.8577 | 37%    | 1.2998 | 30.8787 | 2.0783  |