Decide for conflicting rules

[mmacata]

Depending on the linted files with ruff, the following warnings are shown:

warning: `one-blank-line-before-class` (D203) and `no-blank-line-before-class` (D211) are incompatible. Ignoring `one-blank-line-before-class`.

warning: `multi-line-summary-first-line` (D212) and `multi-line-summary-second-line` (D213) are incompatible. Ignoring `multi-line-summary-second-line`.

This happens because of conflicting pydocstyle rules https://docs.astral.sh/ruff/rules/#pydocstyle-d

This PR decides which ones to ignore. It is merged with the repo specific rules to ignore and cannot be overwritten by repo specific rules to ignore.

[griembauer]

Personally I like the style multi-line-summary-second-line better, so I'd opt to ignore the other one. But that's just personal preference I guess.
For the class definitions I have no preferences

[anikaweinmann]

I am also for the compact rules which Carmen selected.

[mmacata]

Ok then I will merge :)