Copy current WAL in consistent state during checkpoint #1894

Job	Run time
build-examples	10m 20s
build-fuzzers	8m 28s
build-linux-arm	13m 26s
build-linux	16m 27s
build-linux-clang10-asan	16m 12s
build-linux-clang10-clang-analyze	16m 44s
build-linux-clang10-mini-tsan	23m 24s
build-linux-clang10-ubsan	16m 4s
build-linux-clang-13-no_test_run	7m 2s
build-linux-cmake-mingw	11m 55s
build-linux-clang-no_test_run	11m 29s
build-linux-cmake-with-benchmark	18m 31s
build-linux-cmake-with-folly	26m 10s
build-linux-cmake-with-folly-lite-no-test	7m 49s
build-linux-cmake-with-folly-coroutines	28m 33s
build-linux-encrypted_env-no_compression	15m 21s
build-linux-gcc-10-cxx20-no_test_run	9m 8s
build-linux-gcc-11-no_test_run	9m 47s
build-linux-gcc-7-with-folly	25m 10s
build-linux-gcc-7-with-folly-lite-no-test	7m 41s
build-linux-gcc-8-no_test_run	8m 20s
build-linux-java-static	11m 35s
build-linux-mini-crashtest	29m 4s
build-linux-java	14m 50s
build-linux-java-pmd	11m 30s
build-linux-release	13m 47s
build-linux-release-rtti	12m 4s
build-linux-static_lib-alt_namespace-status_checked	18m 39s
build-linux-unity-and-headers	12m 48s
build-macos	43m 24s
build-macos-cmake (true)	41m 49s
build-macos-java	24m 31s
build-macos-java-static	27m 17s
build-macos-cmake (false)	40m 54s
build-macos-java-static-universal	22m 52s
check-format-and-targets	26s
build-windows-vs2019	51m 12s
	11h 24m 43s

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