[SPARK-55910][SQL][TESTS] Merge SQLTestUtilsBase/SQLTestUtils into QueryTestBase/QueryTest

### What changes were proposed in this pull request?

Merge both test utility hierarchies into one:
- Move all `SQLTestUtilsBase` methods into `QueryTestBase`
- Change `QueryTest` from abstract class to trait, move all `SQLTestUtils` methods into it
- Make `SQLTestUtilsBase` and `SQLTestUtils` thin empty aliases

**Changes in `QueryTest.scala`:**

*`QueryTestBase` (trait):*
- Add `Eventually`, `BeforeAndAfterAll`, `SQLTestData` mixins
- Move all methods from `SQLTestUtilsBase`: `testImplicits`, `sql`, `sparkContext`, `withSQLConf`, `withTable`, `withView`, `withTempView`, `withGlobalTempView`, `withDatabase`, `withNamespace`, `withCache`, `uncacheTable`, `withTempDatabase`, `withCurrentCatalogAndNamespace`, `withLocale`, `withSessionVariable`, `withUserDefinedFunction`, `activateDatabase`, `stripSparkFilter`, `logicalPlanToSparkQuery`, `makeQualifiedPath`, `testFile`, `getLocalDirSize`

*`QueryTest` (changed from abstract class to trait):*
- Add `PlanTest` mixin
- Move all methods from `SQLTestUtils`: `setupTestData`, `loadTestData`, `beforeAll`, `withTempDir`, `testWithWholeStageCodegenOnAndOff`, `testQuietly`, `test` override (DisableAdaptiveExecution), `testWithUninterruptibleThread`, `withResourceTempPath`, `waitForTasksToFinish`, `withTempPaths`
- Fix `getCurrentClassCallSitePattern` and `getNextLineCallSitePattern` to use `lastIndexWhere` for stack frame lookup — trait default methods may add mixin forwarder frames that shift the stack layout

**Changes in `SQLTestUtils.scala`:**
- `SQLTestUtilsBase` → empty trait alias of `QueryTestBase`
- `SQLTestUtils` → empty trait alias of `QueryTest`
- `object SQLTestUtils.compareAnswers` kept as-is

**Unused import fixes:**
- `AlterTableTests.scala` — removed unused `QueryTest.checkAnswer` static import
- `HivePlanTest.scala` — removed unused `import spark.sql` (now inherited)

### Why are the changes needed?

Consolidates two parallel test utility hierarchies (`QueryTestBase`/`QueryTest` and `SQLTestUtilsBase`/`SQLTestUtils`) into one. Previously they shared `PlanTestBase` and `SparkSessionProvider` but were maintained as separate hierarchies, causing confusion about which to extend.

After this PR:
```
QueryTestBase (trait — has all base utilities from both old QueryTestBase + SQLTestUtilsBase)
└── QueryTest (trait — has all test-registration methods from both old QueryTest + SQLTestUtils)
    ├── SQLTestUtils (empty alias)
    └── SQLTestUtilsBase (empty alias, also extends QueryTestBase)
```

Changing `QueryTest` from abstract class to trait enables `SQLTestUtils` to extend it directly, and allows test suites to mix in `QueryTest` alongside `SparkFunSuite` or `SparkPlanTest` without inheritance conflicts.

### Semantic change: `DisableAdaptiveExecution` tag handling

The `test()` override that honors `DisableAdaptiveExecution` previously lived only on `SQLTestUtils`. Moving it onto `QueryTest` means every `extends QueryTest` suite now honors the tag — including ones that previously didn't (e.g., `HivePlanTest` and a handful of connector suites that extend `QueryTest` directly without going through `SharedSparkSession`). No live regression today since all current `DisableAdaptiveExecution` usages go through `SharedSparkSession`, but this is a semantic expansion beyond just moving methods between traits.

### Does this PR introduce _any_ user-facing change?

No.

### How was this patch tested?

- CI compilation across all modules
- Locally verified affected tests pass (DataFrameFunctionsSuite, ReplaceIntegerLiteralsWithOrdinalsDataframeSuite, QueryTestSuite)

### Was this patch authored or co-authored using generative AI tooling?

Generated-by: Claude Code (claude-opus-4-6)

Closes #55381 from zhengruifeng/sql_merge_utils_into_query.

Authored-by: Ruifeng Zheng <ruifengz@apache.org>
Signed-off-by: Ruifeng Zheng <ruifengz@foxmail.com>

Author: zhengruifeng