refactor: Replace getDbType with LoadLevel name

[ph3636]

refactor: Replace TableMetaCache and UndoLogManager and UndoExecutorHolder and KeywordChecker and SQLOperateRecognizerHolder with LoadLevel

[codecov-io]

Codecov Report

Merging #2208 into develop will decrease coverage by 0.15%.
The diff coverage is 0%.

@@              Coverage Diff              @@
##             develop    #2208      +/-   ##
=============================================
- Coverage      53.04%   52.88%   -0.16%     
+ Complexity      2500     2498       -2     
=============================================
  Files            485      485              
  Lines          15305    15302       -3     
  Branches        1755     1724      -31     
=============================================
- Hits            8118     8093      -25     
+ Misses          6411     6407       -4     
- Partials         776      802      +26

Impacted Files	Coverage Δ	Complexity Δ
...ava/io/seata/core/constants/ConfigurationKeys.java	0% <ø> (ø)	0 <0> (ø)	⬇️
...eata/core/rpc/netty/AbstractRpcRemotingServer.java	0% <0%> (ø)	0 <0> (ø)	⬇️
...ava/io/seata/core/rpc/netty/NettyServerConfig.java	0% <0%> (ø)	0 <0> (ø)	⬇️
...re/properties/registry/ConfigApolloProperties.java	0% <0%> (ø)	0 <0> (ø)	⬇️
...obuf/convertor/BranchRegisterRequestConvertor.java	90.47% <0%> (-9.53%)	3% <0%> (ø)
...otobuf/convertor/GlobalBeginResponseConvertor.java	92.59% <0%> (-7.41%)	3% <0%> (ø)
...otobuf/convertor/GlobalStatusRequestConvertor.java	93.75% <0%> (-6.25%)	3% <0%> (ø)
...otobuf/convertor/GlobalCommitRequestConvertor.java	93.75% <0%> (-6.25%)	3% <0%> (ø)
...obuf/convertor/GlobalRollbackRequestConvertor.java	93.75% <0%> (-6.25%)	3% <0%> (ø)
...protobuf/convertor/RegisterTMRequestConvertor.java	94.73% <0%> (-5.27%)	3% <0%> (ø)
... and 19 more

[slievrly]

LGTM

[zjinlei]

LGTM