ref(seer): Read project preferences only from Sentry DB, part 1

[srest2021]

Relates to CW-1175

First step in migrating project-preference reads off the Seer API. Flips the following read call sites to read from the Sentry DB and removes the organizations:seer-project-settings-read-from-sentry flag from them. Writes still dual-write via the Seer API. Types tightened where possible.

Modified callsites:

• ProjectSeerPreferencesEndpoint.get
• Seer RPCs get_project_preferences / bulk_get_project_preferences
• has_project_connected_repos and removed the Seer API cache (no longer needed for a local DB hit)
• Deleted the bulk_read_preferences wrapper and _resolve_project_preference; callers use bulk_read_preferences_from_sentry_db / read_preference_from_sentry_db directly. _call_autofix now derives repos from preference.repositories itself.
• night shift _get_eligible_projects and context engine index_repos consume typed SeerProjectPreference objects directly instead of dict round-tripping

Affected tests updated to create real SeerProjectRepository rows and project options instead of mocking the Seer API. Removed tests for now-unreachable Seer-API fallback paths. Most of this large PR is just updated tests :)

[linear-code]

CW-1175 Remove Seer preferences API calls from Sentry

[github-actions]

Backend Test Failures

Failures on 3037f79 in this run:

tests/sentry/tasks/seer/test_context_engine_index.py::TestIndexRepos::test_skips_projects_without_seer_repositories — log

[gw0] linux -- Python 3.13.1 /home/runner/work/sentry/sentry/.venv/bin/python3
tests/sentry/tasks/seer/test_context_engine_index.py:399: in test_skips_projects_without_seer_repositories
    assert repos[0]["project_ids"] == ["getsentry"]
E   AssertionError: assert [4558019327033360] == ['getsentry']
E     
E     At index 0 diff: 4558019327033360 != 'getsentry'
E     
E     Full diff:
E       [
E     -     'getsentry',
E     +     4558019327033360,
E       ]

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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