Use ParentInstances iterator for parent_instance_id #120

Job	Run time
cargo-deny (advisories)	43s
lint	38s
cargo-deny (bans licenses sources)	55s
aarch64-apple-ios / build	1m 1s
aarch64-apple-darwin / build	1m 5s
aarch64-apple-darwin-nightly / build	50s
aarch64-unknown-linux-gnu / build	41s
aarch64-unknown-linux-musl / build	1m 12s
arm-linux-androideabi / build	35s
armv7-linux-androideabi / build	37s
i686-pc-windows-gnu / build	2m 25s
i686-pc-windows-msvc / build	2m 20s
i686-unknown-linux-gnu / build	42s
i686-unknown-linux-musl / build	1m 10s
msrv-aarch64-apple-darwin / build	2m 27s
msrv-arm-linux-androideabi / build	2m 36s
msrv-x86_64-pc-windows-msvc / build	3m 2s
msrv-x86_64-unknown-freebsd / build	2m 31s
msrv-x86_64-unknown-linux-gnu / build	2m 44s
msrv-x86_64-unknown-linux-musl / build	3m 25s
x86_64-apple-darwin / build	56s
msrv-x86_64-unknown-netbsd / build	2m 28s
x86_64-pc-windows-gnu / build	2m 2s
x86_64-pc-windows-msvc / build	2m 4s
x86_64-pc-windows-msvc-nightly / build	1m 58s
x86_64-unknown-freebsd / build	27s
x86_64-unknown-linux-gnu / build	2m 44s
x86_64-unknown-linux-gnu-nightly / build	1m 46s
x86_64-unknown-linux-musl / build	3m 20s
x86_64-unknown-netbsd / build	32s
	49m 56s

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