ref: move the rest of NOSTORE options to django settings

[joshuarli]

followup to #117102 which has been proven. again, this will go through the same 3-stage rollout:

• this merges
• https://github.com/getsentry/getsentry/pull/20667 merges
• cleanup the options_mapper entry, register() call, and SENTRY_LOGGING_FORMAT = DEAD

smoke test that this is still compatible (thanks to options_mapper) with getsentry master:

import os, warnings

os.environ.setdefault("SENTRY_CONF", "getsentry/settings.py")

from sentry.runner import configure
configure()

from django.conf import settings
from sentry.conf.server import DEAD
from sentry.runner.initializer import bootstrap_options, validate_options

# system.base-hostname: a key this branch moved into options_mapper.
# getsentry master still sets it via the OPTION form; verify it bridges into the setting.
KEY, SETTING = "system.base-hostname", "SENTRY_BASE_HOSTNAME"

# boot: getsentry's SENTRY_OPTIONS[KEY] is promoted into settings.SENTRY_BASE_HOSTNAME
assert getattr(settings, SETTING) is not DEAD, "setting never promoted from option"
assert getattr(settings, SETTING) == settings.SENTRY_OPTIONS[KEY], (
    getattr(settings, SETTING),
    settings.SENTRY_OPTIONS[KEY],
)

# deploy re-bootstrap: setting starts DEAD, option is written, bridge promotes it back
setattr(settings, SETTING, DEAD)
settings.SENTRY_OPTIONS[KEY] = "example.test"
bootstrap_options(settings)
assert getattr(settings, SETTING) == "example.test", getattr(settings, SETTING)

# still registered -> no unknown-option warning / crash
with warnings.catch_warnings(record=True) as w:
    warnings.simplefilter("always")
    validate_options(settings)
assert not [m for m in (str(x.message) for x in w) if KEY in m]

print(f"OK: {KEY} option-form config bridges into settings.{SETTING}")

[cursor]

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

^{❌ Bugbot Autofix is OFF. To automatically fix reported issues with cloud agents, enable autofix in the Cursor dashboard.}

^{Reviewed by Cursor Bugbot for commit 5342e5e. Configure here.}

[markstory]

Looks good to me. The extra layer of settings shims is 😵.