ref(api): Move to_valid_int_id to a more central location

[kcons]

It started in workflow_engine, but now it's used in a variety of places.

[github-actions]

Backend Test Failures

Failures on 596feda in this run:

tests/symbolicator/test_minidump_full.py::SymbolicatorMinidumpIntegrationTest::test_full_minidump_json_extra — log

[gw1] linux -- Python 3.13.1 /home/runner/work/sentry/sentry/.venv/bin/python3
tests/symbolicator/test_minidump_full.py:124: in test_full_minidump_json_extra
    event = self.post_and_retrieve_minidump(
src/sentry/testutils/relay.py:127: in post_and_retrieve_minidump
    assert resp.ok
E   assert False
E    +  where False = <Response [503]>.ok