chore: remove contrib/ directory #17432

Job	Run time
Lint Rust	7m 31s
cargo deny	35s
Check if node constants are up to date	2s
Check provider database	5s
Rust doc comments	22s
Build C library (ubuntu-latest)	2m 24s
Build C library (macos-latest)	8m 21s
Build deltachat-rpc-server (ubuntu-latest)	7m 39s
Build deltachat-rpc-server (macos-latest)	2m 44s
Rust tests (ubuntu-latest, 1.83.0)	9m 14s
Build deltachat-rpc-server (windows-latest)	20m 5s
Rust tests (windows-latest, 1.83.0)	20m 28s
Rust tests (macos-latest, 1.83.0)	7m 33s
Rust tests (ubuntu-latest, 1.81.0)	9m 16s
Python lint	11s
CFFI Python tests (ubuntu-latest, 3.13)	6m 58s
CFFI Python tests (macos-latest, 3.13)	3m 53s
CFFI Python tests (ubuntu-latest, pypy3.10)	6m 7s
CFFI Python tests (macos-latest, pypy3.10)	4m 32s
CFFI Python tests (ubuntu-latest, 3.7)	5m 17s
JSON-RPC Python tests (ubuntu-latest, 3.13)	2m 18s
JSON-RPC Python tests (macos-latest, 3.13)	1m 28s
JSON-RPC Python tests (windows-latest, 3.13)	2m 47s
JSON-RPC Python tests (ubuntu-latest, pypy3.10)	2m 7s
JSON-RPC Python tests (macos-latest, pypy3.10)	2m 0s
JSON-RPC Python tests (ubuntu-latest, 3.7)	1m 54s
	2h 15m 51s

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