Fix potential metadata corrupt in Redis caused by gc

[davies]

The gc command will scan all the entries and inodes to find out dangling (not used by any entry) inodes. The scanning of entries is not atomic, so we ignore all the inodes (checking the atime) created in last hour. There is still a chance that a inode was renamed and both the old name and new name are missed from the scanning, then the inode will be identify as dangling and deleted.

This PR change it to check the Ctime of inode, ignore the inodes that was created or renamed within a hour.

[codecov-commenter]

Codecov Report

Merging #1110 (1c0ccce) into main (1eaa406) will increase coverage by 0.42%.
The diff coverage is 84.61%.

@@             Coverage Diff              @@
##               main    #1110      +/-   ##
============================================
+ Coverage     53.24%   53.66%   +0.42%     
- Complexity      149      167      +18     
============================================
  Files           146      146              
  Lines         23050    22989      -61     
  Branches        422      410      -12     
============================================
+ Hits          12272    12337      +65     
+ Misses         9253     9129     -124     
+ Partials       1525     1523       -2     

Impacted Files	Coverage Δ
pkg/meta/redis.go	71.15% <0.00%> (ø)
.../src/main/java/io/juicefs/JuiceFileSystemImpl.java	65.16% <83.33%> (+7.96%)	⬆️
pkg/meta/base.go	75.65% <100.00%> (ø)
pkg/meta/sql.go	67.73% <100.00%> (+0.27%)	⬆️
pkg/vfs/writer.go	78.64% <0.00%> (-1.02%)	⬇️
pkg/vfs/reader.go	79.56% <0.00%> (+2.91%)	⬆️
...src/main/java/io/juicefs/utils/ConsistentHash.java	76.66% <0.00%> (+3.33%)	⬆️
...main/java/io/juicefs/utils/RedefineClassAgent.java	53.57% <0.00%> (+7.14%)	⬆️

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