recycle: optimize the recycling progress by reducing one redundant RENAME operation.

[LykxSassinator]

Description

This pr is used for optimizing the progress of recycle, by eliminating one redundant RENAME operation. In this pr:

• recycle won't RENAME append logs to reserved.log anymore.
• recycle progress has been reverted back to the previous work, just moving the logical purged files into another container, named with stale_files.
• When dropping the PipeLog, all stale files will be cleaned to reduce the later recovery time-cost.

[codecov[bot]]

Codecov Report

Patch coverage: 98.30% and project coverage change: -0.05 :warning:

Comparison is base (205b5d7) 97.92% compared to head (250d049) 97.88%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #308 +/- ## ========================================== - Coverage 97.92% 97.88% -0.05% ========================================== Files 31 31 Lines 12189 12226 +37 ========================================== + Hits 11936 11967 +31 - Misses 253 259 +6 ``` | [Impacted Files](https://app.codecov.io/gh/tikv/raft-engine/pull/308?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=tikv) | Coverage Δ | | |---|---|---| | [src/file\_pipe\_log/mod.rs](https://app.codecov.io/gh/tikv/raft-engine/pull/308?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=tikv#diff-c3JjL2ZpbGVfcGlwZV9sb2cvbW9kLnJz) | `98.45% <ø> (ø)` | | | [src/file\_pipe\_log/pipe\_builder.rs](https://app.codecov.io/gh/tikv/raft-engine/pull/308?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=tikv#diff-c3JjL2ZpbGVfcGlwZV9sb2cvcGlwZV9idWlsZGVyLnJz) | `96.05% <97.22%> (+0.07%)` | :arrow_up: | | [src/file\_pipe\_log/pipe.rs](https://app.codecov.io/gh/tikv/raft-engine/pull/308?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=tikv#diff-c3JjL2ZpbGVfcGlwZV9sb2cvcGlwZS5ycw==) | `98.16% <98.21%> (+0.08%)` | :arrow_up: | | [src/engine.rs](https://app.codecov.io/gh/tikv/raft-engine/pull/308?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=tikv#diff-c3JjL2VuZ2luZS5ycw==) | `98.63% <100.00%> (+<0.01%)` | :arrow_up: | | [src/file\_pipe\_log/format.rs](https://app.codecov.io/gh/tikv/raft-engine/pull/308?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=tikv#diff-c3JjL2ZpbGVfcGlwZV9sb2cvZm9ybWF0LnJz) | `99.05% <100.00%> (ø)` | | ... and [2 files with indirect coverage changes](https://app.codecov.io/gh/tikv/raft-engine/pull/308/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=tikv)

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[LykxSassinator]

/cc @tabokie PTAL, thx.

[LykxSassinator]

As the related work in this pr has been merged into the pr: https://github.com/tikv/raft-engine/pull/310, this pr can be closed.