[Pools] Fix issues with member migration to `DelegateStake` #5728

Job	Run time
check-dependency-rules	8s
check-markdown	19s
check-workspace	19s
set-image	7s
check-rust-feature-propagation	1m 54s
test-rust-features	1m 52s
check-toml-format	53s
check-umbrella	2m 8s
fmt	1m 3s
	8m 43s

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