[Refactor] refactor sample statistics process(part 1)

[packy92]

Why I'm doing:

Sample statistics collec job may only sample the rows in front of the tablet, which may lead to a wide margin of error in ndv.

What I'm doing:

Stratify tablets into four weight levels according to the number of tablet rows. Set the tablet sampling rate and row sampling rate for each level to ensure random sampling of data as much as possible. This pr cannot improve the accuracy of min and max values. Subsequent pr will solve this problem. Fixes #issue

What type of PR is this:

• [ ] BugFix
• [ ] Feature
• [ ] Enhancement
• [x] Refactor
• [ ] UT
• [ ] Doc
• [ ] Tool

Does this PR entail a change in behavior?

• [ ] Yes, this PR will result in a change in behavior.
• [x] No, this PR will not result in a change in behavior.

If yes, please specify the type of change:

• [ ] Interface/UI changes: syntax, type conversion, expression evaluation, display information
• [ ] Parameter changes: default values, similar parameters but with different default values
• [x] Policy changes: use new policy to replace old one, functionality automatically enabled
• [ ] Feature removed
• [ ] Miscellaneous: upgrade & downgrade compatibility, etc.

Checklist:

• [x] I have added test cases for my bug fix or my new feature
• [ ] This pr needs user documentation (for new or modified features or behaviors)
  • [ ] I have added documentation for my new feature or new function
• [ ] This is a backport pr

Bugfix cherry-pick branch check:

• [x] I have checked the version labels which the pr will be auto-backported to the target branch
  • [x] 3.3
  • [ ] 3.2
  • [ ] 3.1
  • [ ] 3.0
  • [ ] 2.5