refactor job manager part1

[panda-sheep]

What type of PR is this?

• bug
• feature
• enhancement

What problem(s) does this PR solve?

Issue(s) number:

Description:

refactor job manager, this pr mainly did the following parts

1. separation by space

2. Remove job_concurrency
   Because only compact and flush, stats syntax supports job_concurrency, and job passes job_concurrency to task, but the corresponding task does not use job_concurrency.
   Even using job_concurrency does not make much sense, because in a space, compactTask and flushTask are concurrent on the storage according to the number of engines. statsTask is concurrent according to the number of parts. FLAGS_max_concurrent_subtasks is enough

3. Fix bugs, such as Call thrift RunAdminJob to create a balance job, if space not existed, the job is still created #3743

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 .....

[pengweisong]

Good Job, LGTM

[critical27]

Generally LGTM.

[critical27]

The job manager will have one queue for one space later, right?

[panda-sheep]

Yes, the later pr will do the following work:
Each space has a priority queue.
Jobs in the same space are executed serially according to priority.
Jobs in different spaces are executed in parallel according to the space.

[liuyu85cn]

good job