Add inject req and pressure spec and reconcile logic

[moomman]

1. add spec to specify inject pressure and job
2. add reconcile logic to control

#272

[codecov-commenter]

Codecov Report

Merging #303 (b6ab606) into main (46be6a7) will decrease coverage by 13.31%.
The diff coverage is 49.06%.

@@             Coverage Diff             @@
##             main     #303       +/-   ##
===========================================
- Coverage   62.36%   49.06%   -13.31%     
===========================================
  Files           2        8        +6     
  Lines         279      856      +577     
===========================================
+ Hits          174      420      +246     
- Misses        103      368      +265     
- Partials        2       68       +66     

Impacted Files	Coverage Δ
pitr/cli/internal/pkg/shardingsphere-proxy.go	0.00% <0.00%> (ø)
pitr/cli/internal/pkg/local-storage.go	42.73% <42.73%> (ø)
pitr/cli/internal/cmd/restore.go	44.58% <44.58%> (ø)
pitr/cli/internal/cmd/show.go	56.09% <56.09%> (ø)
pitr/cli/internal/cmd/backup.go	58.87% <58.87%> (ø)
pitr/cli/internal/pkg/agent-server.go	72.54% <72.54%> (ø)
pitr/cli/pkg/gsutil/conn.go	76.47% <76.47%> (ø)
pitr/cli/pkg/stringutil/rand_string.go	91.30% <91.30%> (ø)

... and 1 file with indirect coverage changes

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