Further improvement of PageStorgae V3

[JaySon-Huang]

Enhancement

We release storage.format_version = 4 and enable PageStorage V3 by default in the v6.1 #3594. There are some improvements remain. Here is the tracking issue of all improvements.

• Polish the debugging tools
  • Make it a subcommand of tiflash binary
  • Make it can dump the encrypted data page_ctl does not support read encryption files. #4962
  • proxy support provide decryption/encryption service without raftstore #5122
• Remove the data of PageStorage V2 after all data has been migrated to V3 #5336
• Polish the performance testing tools
  • Make it a subcommand of tiflash binary feat: add page_stress_testing as a subcommand of tiflash #5037
• Support decreasing the file limit size of BlobFile #5558
• PageStorage: Evicting stale reading snapshots #6056
• [P2] Optimize the restore speed PageStorage V3 restore takes longer than V2 #4914
• [P2] Compression on serialized entries (in WAL), which can optimize the serialized data length for wide tables PageStorage: compression of the fields offset in PageEntry #4996
• [P2] Continuously fields can read by one system call in BlobStore::read #5078
• [P3] Split the pipeline of persisting write batch into smaller parts and speed up the throughput for WALStore
• [P3] Remove embedded member function for gtest in dbms/src/Storages/Page #4562
• Clean potential obsolete data which can never be deleted in PageStorage  #5675
• PageStorage gc may take long time in removing external pages from all tables #5700
• page-ctl cannot work when there is an unresolved page ref #5568
• Universal PageStorage #6071
• More metrics about PageStorage #6162