Skip internal keys' lookup in LRU for the DefaultCache. #1919

Job	Run time
PSV.Linux.22.04.gcc9.Cpplint	8m 13s
PSV.Linux.22.04.gcc9.OLP_SDK_ENABLE_DEFAULT_CACHE=OFF	2m 14s
PSV.Linux.22.04.gcc9.Tests.CodeCov	9m 55s
PSV.Linux.22.04.gcc11	8m 7s
PSV.Linux.latest.gcc14.OLP_SDK_ENABLE_DEFAULT_CACHE=OFF	2m 38s
PSV.Linux.22.04.gcc13	13m 59s
PSV.Linux.22.04.clang	9m 8s
PSV.Linux.22.04.gcc11.OLP_SDK_ENABLE_DEFAULT_CACHE=OFF	2m 3s
PSV.Linux.Android.22.04	7m 57s
PSV.MacOS14.Xcode15	4m 25s
PSV.MacOS13.Xcode15.x86_64	3m 54s
PSV.iOS.MacOS13.Xcode14	9m 32s
PSV.MacOS15.Xcode16	4m 20s
PSV.iOS.MacOS13.Xcode15	14m 36s
PSV.iOS.MacOS15.Xcode16	6m 15s
PSV.iOS.MacOS14.Xcode15	8m 25s
PSV.Win.VC2022	10m 1s
PSV.Commit.Checker	11s
	2h 5m 53s

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