### What problem does this PR solve?
doris 3.x not need this fix because the legacy planner already be
deleted
what's wrong:
1. when nereids planner can not parse the sql, doris will fallback to
legacy planner and maybe handle this case, but we not set the
`enable_nereids_planner` to `false` for legacy planner
2. the `ignore_storage_data_distribution` only support when
`enable_nereids_planner` is `true`
3. the legacy planner will use one phase aggregation when input fragment
only has one instance
4. the legacy planner maybe compute one instance by invoke
`OlapScanNode#getNumInstances()` if `enable_nereids_planner == true &&
ignore_storage_data_distribution == true`, even the data place at
multiple backends, then the aggregation will compute wrong result
so when fallback to legacy planner, the legacy planner should set
`enable_nereids_planner` to `false`, then the input OlapScanNode will
not compute one instance, and the AggregationNode will use two phases to
compute the right result.
### Check List (For Author)
- Test <!-- At least one of them must be included. -->
- [x] Regression test
- [ ] Unit Test
- [ ] Manual test (add detailed scripts or steps below)
- [ ] No need to test or manual test. Explain why:
- [ ] This is a refactor/code format and no logic has been changed.
- [ ] Previous test can cover this change.
- [ ] No code files have been changed.
- [ ] Other reason <!-- Add your reason? -->
- Behavior changed:
- [x] No.
- [ ] Yes. <!-- Explain the behavior change -->
- Does this need documentation?
- [x] No.
- [ ] Yes. <!-- Add document PR link here. eg:
https://github.com/apache/doris-website/pull/1214 -->
### Check List (For Reviewer who merge this PR)
- [ ] Confirm the release note
- [ ] Confirm test cases
- [ ] Confirm document
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c83c2e18bc