chore(graphene): Drop transaction-based tracing

[pnagre05]

Description

I removed the transaction-based tracing fallback from the graphene integration - I did this by doing the following

• Removed all is_span_streaming_enabled branching and enforces the unconditional use of sentry_sdk.traces.start_span
• Removed legacy compatibility utilities like the else: fallback blocks and the legacy __exit__ context manager calls
• Deleted obsolete transaction-based tests and promotes the span streaming tests to standard tests by removing their _span_streaming suffixes

Issues

• resolves: Remove transaction-based tracing from graphene #7091

Reminders

• Please add tests to validate your changes, and lint your code using uv run ruff.
• Add GH Issue ID & Linear ID (if applicable)
• PR title should use conventional commit style (feat:, fix:, ref:, meta:)
• For external contributors: CONTRIBUTING.md, Sentry SDK development docs, Discord community

[sentrivana]

Hey @pnagre05, I had a quick look and the PR looks good.

Looks like there would be some reformatting by ruff:

Run uv run ruff format --check tests sentry_sdk
warning: No `requires-python` value found in the workspace. Defaulting to `>=3.14`.
unformatted: File would be reformatted
   --> tests/integrations/graphene/test_graphene.py:444:54
    |
443 |
    - def test_breadcrumbs_hold_query_information_on_error(
    -     sentry_init, capture_items
    - ):
444 + def test_breadcrumbs_hold_query_information_on_error(sentry_init, capture_items):
445 |     sentry_init(
    |

1 file would be reformatted, 464 files already formatted
Error: Process completed with exit code 1.

Please run ruff on the changes. You can also install pre-commit and let it automatically run all the linting checks before committing. Guides how to do both should be in our CONTRIBUTING.md.

Feel free to set this as ready for review once the linting is green locally.

[pnagre05]

Made the changes, marking it as ready for review now