only create 1 part in tck

[critical27]

What type of PR is this?

• bug
• feature
• enhancement

What problem(s) does this PR solve?

Issue(s) number:

Description:

Backport from https://github.com/vesoft-inc/nebula-ent/pull/1364. Only create space with 1 part in all tck/pytest cases. (There are even space with 1000 parts before... This will make ent version ci quite unstable, because we need to create RocksDB for each part) Hope ci could handle it now, especially in ent version.

How do you solve it?

Special notes for your reviewer, ex. impact of this fix, design document, etc:

Checklist:

Tests:

• Unit test(positive and negative cases)
• Function test
• Performance test
• N/A

Affects:

• Documentation affected (Please add the label if documentation needs to be modified.)
• Incompatibility (If it breaks the compatibility, please describe it and add the label.）
• If it's needed to cherry-pick (If cherry-pick to some branches is required, please label the destination version(s).)
• Performance impacted: Consumes more CPU/Memory

Release notes:

Please confirm whether to be reflected in release notes and how to describe:

ex. Fixed the bug .....

[Shylock-Hg]

Why change this? I think we should test one and more partitions.

[critical27]

In tck, there is only one storage, what is the point to use multiple partitions?

[Shylock-Hg]

Test code logic of partitions.