ci: Enable feature_init and wallet_reorgsrestore in valgrind task #32519

The fork() isn't needed and in fact makes the forked process not react to signals (like kill or terminate), so just avoid it and run the valgrind process directly in the CI task.

Can be tested with something like:

env -i HOME="$HOME" PATH="$PATH" USER="$USER" MAKEJOBS="-j$(nproc)" FILE_ENV="./ci/test/00_setup_env_native_valgrind.sh" ./ci/test_run_all.sh

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Code Coverage & Benchmarks

For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/32519.

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If someone wants to quickly test this outside the CI system a minimal reproducer would be:

───────┬────────────────────────────────────────────────────────────────────────
       │ File: /tmp/a.py
───────┼────────────────────────────────────────────────────────────────────────
   1   │ import subprocess
   2   │ import time
   3   │ 
   4   │ process = subprocess.Popen(["bash", "/tmp/a.sh"])
   5   │ print("Wait for the first print to happen ...")
   6   │ time.sleep(0.1)
   7   │ process.kill()
   8   │ print(f"Process ended with {process.wait()}. Should not print more!")
───────┴────────────────────────────────────────────────────────────────────────
───────┬────────────────────────────────────────────────────────────────────────
       │ File: /tmp/a.sh
───────┼────────────────────────────────────────────────────────────────────────
   1   │ exec bash -c 'echo hi1 && sleep 1 && echo hi2 && false'
───────┴────────────────────────────────────────────────────────────────────────

Command: python3 /tmp/a.py

ACK fa2be605fee42c1286de2ddefbec976dde2c35ba - x86_64, aarch64