feat(loguru): Make Logs the primary feature

[sentrivana]

Description

Get the Loguru integration into shape now that Sentry Logs is a first-class feature. The idea is to make Logs the primary feature the integration offers, with capturing events an optional add-on.

High-level overview of the changes:

• The integration has to be enabled explicitly by the user. It's not auto-enabled anymore.
• Sentry logs related options and features get more generic sounding names.
  • For instance, level (before: sentry_logs_level) now sets the Sentry logs level.
  • Existing secondary features with previously generic names get specialized names (level -> breadcrumb_level).
• Capturing Sentry logs is on by default when the integration is enabled.
• Event capture is off by default, but can be turned on via an option. Breadcrumb capture is still on by default.
• The capture_sentry_logs option is gone completely. Since logs instrumentation is now on by default, and the level option exists, it was superfluous. Capturing logs can still be opted out of by setting level=None.

Issues

Closes #7247
Closes https://linear.app/getsentry/issue/PY-2740/update-loguru-integration

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[github-actions]

Codecov Results 📊

✅ 110495 passed | ⏭️ 5428 skipped | Total: 115923 | Pass Rate: 95.32% | Execution Time: 384m 12s

📊 Comparison with Base Branch

Metric	Change
Total Tests	📉 -8478
Passed Tests	📉 -7172
Failed Tests	📉 -2
Skipped Tests	📉 -1304

➖ Removed Tests (2)

View removed tests

• test_continuous_profiler_auto_start_and_stop_sampled[non-experiment-gevent]
  • File: tests.profiler.test_continuous_profiler
• test_continuous_profiler_auto_start_and_stop_sampled_span_streaming[experiment-gevent]
  • File: tests.profiler.test_continuous_profiler

All tests are passing successfully.

✅ Patch coverage is 100.00%. Project has 2268 uncovered lines.
✅ Project coverage is 90.51%. Comparing base (base) to head (head).

Files with missing lines (1)

File	Patch %	Lines
sentry_sdk/integrations/loguru.py	100.00%	⚠️ 1 partials

Coverage diff

@@            Coverage Diff             @@
##          main       #PR       +/-##
==========================================
+ Coverage    90.22%    90.51%    +0.29%
==========================================
  Files          193       185        -8
  Lines        25435     23904     -1531
  Branches      9346      8806      -540
==========================================
+ Hits         22947     21636     -1311
- Misses        2488      2268      -220
- Partials      1434      1378       -56

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[linear-code]

PY-2740