Update flyweight from develop #2472

Job	Run time
b2-windows (windows-2019)	28m 31s
cmake-install-posix (ubuntu-20.04)	4m 13s
b2-windows (windows-2022)	30m 7s
b2-posix (ubuntu-20.04)	12m 20s
cmake-install-posix (ubuntu-22.04)	4m 26s
cmake-install-windows (windows-2019)	9m 32s
b2-posix (ubuntu-22.04)	12m 56s
cmake-install-posix (macos-12)	7m 20s
cmake-install-windows (windows-2022)	8m 9s
cmake-test-posix (ubuntu-latest)	34m 38s
b2-posix (macos-12)	24m 27s
cmake-install-posix (macos-13)	9m 37s
b2-posix (macos-13)	23m 16s
cmake-install-posix (macos-14)	4m 41s
b2-posix (macos-14)	10m 23s
cmake-test-posix-quick (ubuntu-20.04)	2m 2s
cmake-test-windows-quick (windows-2019)	5m 3s
cmake-test-posix-quick (ubuntu-22.04)	1m 41s
cmake-test-windows-quick (windows-2022)	5m 12s
cmake-test-posix-quick (macos-12)	4m 57s
cmake-test-posix-quick (macos-13)	5m 38s
cmake-test-posix-quick (macos-14)	3m 39s
	4h 12m 48s

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