deb: add postinst/postremove actions for systemd #4149

Job	Run time
linux-binary-release (i386, i386)	6m 46s
linux-binary-release (amd64, amd64)	6m 52s
linux-binary-release (armhf, armhf)	6m 24s
linux-binary-release (armel, armel)	6m 22s
linux-binary-release (arm64, aarch64)	6m 42s
linux-binary-release (mipsel, mipsel)	6m 25s
linux-binary-release (mips64el, mips64el)	6m 44s
linux-binary-release (loongarch64, loongarch64)	6m 29s
linux-binary-release (riscv64, riscv64)	6m 34s
linux-binary-release (riscv32, riscv32)	7m 0s
	1h 6m 18s

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