### What changes were proposed in this pull request?
In the PR, I propose to move all tests that use deprecated Spark APIs to separate test classes, and add the annotation:
```scala
deprecated("This test suite will be removed.", "3.0.0")
```
The annotation suppress warnings from already deprecated methods and classes.
### Why are the changes needed?
The warnings about deprecated Spark APIs in tests does not indicate any issues because the tests use such APIs intentionally. Eliminating the warnings allows to highlight other warnings that could show real problems.
### Does this PR introduce any user-facing change?
No
### How was this patch tested?
By existing test suites and by
- DeprecatedAvroFunctionsSuite
- DeprecatedDateFunctionsSuite
- DeprecatedDatasetAggregatorSuite
- DeprecatedStreamingAggregationSuite
- DeprecatedWholeStageCodegenSuite
Closes#26885 from MaxGekk/eliminate-deprecate-warnings.
Authored-by: Maxim Gekk <max.gekk@gmail.com>
Signed-off-by: Sean Owen <srowen@gmail.com>
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