See also #32642
`LocationCache` used map to store different locations for different K
which may cause lots of CPU time when get locations many times.
This PR change the implementation of LocationCache to store only the
location for the largest K used to totally remove the map access
operation.
See pprof from test of @XuanYang-cn

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Signed-off-by: Congqi Xia <congqi.xia@zilliz.com>