[bugfix](scanner) olap scanner compute is wrong

[yiguolei]

Proposed changes

This issue is introduced by https://github.com/apache/doris/pull/8096, the operator priority is wrong , so that in some cases, there will be many scanners.

Problem summary

Describe your changes.

Checklist(Required)

1. Does it affect the original behavior:
   • [ ] Yes
   • [ ] No
   • [ ] I don't know
2. Has unit tests been added:
   • [ ] Yes
   • [ ] No
   • [ ] No Need
3. Has document been added or modified:
   • [ ] Yes
   • [ ] No
   • [ ] No Need
4. Does it need to update dependencies:
   • [ ] Yes
   • [ ] No
5. Are there any changes that cannot be rolled back:
   • [ ] Yes (If Yes, please explain WHY)
   • [ ] No

Further comments

If this is a relatively large or complex change, kick off the discussion at [email protected] by explaining why you chose the solution you did and what alternatives you considered, etc...

[github-actions[bot]]

PR approved by at least one committer and no changes requested.

[github-actions[bot]]

PR approved by anyone and no changes requested.