Rename NodeSearch to SearchNode in search node module
### Problem/Motivation
Drupal\node\Plugin\Search\NodeSearch was moved into the new search_node core sub-module and renamed to Drupal\search_node\Plugin\Search\SearchNode in drupal:11.4.0. NodeSearch survives as a deprecated subclass until drupal:12.0.0.
### Proposed resolution
Handled automatically by drupal-rector by configuring the existing upstream rule in the Drupal 12 rule set (no dedicated rule class).
### How this rule was built
This rule was produced with an AI-assisted workflow in which every step was verified manually by @bbrala. Its logic started from the matching drupal-digests entry, which was adapted to drupal-rector's conventions — a dedicated rule or an existing upstream rule configured into the Drupal 12 set — and covered with before/after test fixtures. Backward-compatibility was assessed and version-gated: safe rewrites are applied directly, while unsafe ones are wrapped via `DeprecationHelper` or moved to an opt-in breaking set. The rule was then live-tested against a set of contributed modules; where no contrib call site could be found, a static code sample was written in a test module to exercise it. A final automated QA pass covered type-guard, fixture coverage, BC-decision, registration and idempotency checks. Verified against real D11 contrib via rector-live-test: trash.
### References
- Change record(s): [CR-3590298](https://www.drupal.org/node/3590298)
- Related issue(s): [#3587564](https://www.drupal.org/i/3587564)
### Work items
- Commit(s): [a1ddee53a5](https://github.com/palantirnet/drupal-rector/commit/a1ddee53a568)
- Pull request(s): [PR #367](https://github.com/palantirnet/drupal-rector/pull/367)
### Credit
- Implemented by: @bbrala
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*Filed retroactively as part of the Drupal 12 rector coverage effort. Closed as fixed; credit to be applied to the contributors listed above.*
*AI was used extensively to build this rule and to file this issue. See [Dries Buytaert: AI-generated Rector rules for Drupal](https://dri.es/ai-generated-rector-rules-for-drupal) and [Björn Brala: Drupal Rector rules are config, not code. Mostly.](https://www.linkedin.com/pulse/drupal-rector-rules-config-code-mostly-bj%C3%B6rn-brala-vfpwe/).*
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