feat(coordinator): prover task record unique

[georgehao]

Purpose or design rationale of this PR

Describe your change. Make sure to answer these three questions: What does this PR do? Why does it do it? How does it do it?

make the prover_task from one to multiple. but need keep it unique

PR title

Your PR title must follow conventional commits (as we are doing squash merge for each PR), so it must start with one of the following types:

• build: Changes that affect the build system or external dependencies (example scopes: yarn, eslint, typescript)
• ci: Changes to our CI configuration files and scripts (example scopes: vercel, github, cypress)
• docs: Documentation-only changes
• feat: A new feature
• fix: A bug fix
• perf: A code change that improves performance
• refactor: A code change that doesn't fix a bug, or add a feature, or improves performance
• style: Changes that do not affect the meaning of the code (white-space, formatting, missing semi-colons, etc)
• test: Adding missing tests or correcting existing tests

Deployment tag versioning

Has tag in common/version.go been updated?

• No, this PR doesn't involve a new deployment, git tag, docker image tag
• Yes

Breaking change label

Does this PR have the breaking-change label?

• No, this PR is not a breaking change
• Yes

[codecov]

Codecov Report

Merging #845 (07fa55c) into develop (826e847) will increase coverage by 0.19%.
The diff coverage is 14.28%.

@@             Coverage Diff             @@
##           develop     #845      +/-   ##
===========================================
+ Coverage    50.74%   50.93%   +0.19%     
===========================================
  Files           60       60              
  Lines         5624     5601      -23     
===========================================
- Hits          2854     2853       -1     
+ Misses        2526     2505      -21     
+ Partials       244      243       -1     

Flag	Coverage Δ
database	42.85% <ø> (ø)
prover	27.48% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files Changed	Coverage Δ
common/types/message/message.go	51.72% <ø> (ø)
coordinator/internal/orm/chunk.go	0.00% <0.00%> (ø)
coordinator/internal/orm/prover_task.go	11.93% <14.81%> (+0.53%)	⬆️

[0xmountaintop]

in general looks good. can you address @Thegaram's concern #845 (comment)?

(btw the migration has already beome incompatible since #756)