Improve supervisor restart calculation #15169

Job	Run time
Build Erlang/OTP (64-bit)	6m 7s
Event File	3s
Build Erlang/OTP (iOS)	6m 21s
Build Erlang/OTP (Types and Flavors)	8m 25s
Build Erlang/OTP (macOS)	7m 28s
Build Erlang/OTP (Windows)	14m 22s
Build and check documentation	5m 43s
Build Erlang/OTP (32-bit)	10m 14s
Run static analysis	7m 12s
Build Erlang/OTP (cross-compile)	15m 32s
Build Erlang/OTP (clang)	6m 14s
Test Erlang/OTP (stdlib)	34m 23s
Release Erlang/OTP	0s
Test Erlang/OTP (system)	7m 59s
	2h 10m 3s

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