issue: #34298
fix key: null defined in the yaml file.
viper will parse it as "", and yaml v3 will parse it as "null".
Signed-off-by: xianliang.li <xianliang.li@zilliz.com>
See also #30806
`formatKey` may cost lots of CPU on string processing under high QPS
scenario, this PR adds a formattedKeys cache preventing string operation
in each param get value.
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Signed-off-by: Congqi Xia <congqi.xia@zilliz.com>
