refactor(nns): Use ValidAddOrRemoveNodeProvider to represent a valid proposal action #2669

Job	Run time
CI PR Only / Candid compatibility checks	3m 26s
CI PR Only / Quick Feedback Tests	2m 43s
CI PR Only / Generate Config Fixtures	1m 36s
CI PR Only / Bazel Build Fuzzers Archives	19s
CI Main / Cargo Lint Linux	9m 29s
CI Main / Check PULL_REQUEST_BAZEL_TARGETS	30s
CI PR Only / Dependency Scan for PR	12s
CI Main / Cargo Build Linux	10m 18s
CI Main / Bazel Run Fuzzers	10m 50s
CI PR Only / Lock Generate	1m 8s
CI Main / Set Config	2s
CI Main / Bazel Test arm64-linux	4m 31s
CI Main / Bazel Test arm64-darwin	14m 34s
CI Main / pocket-ic-tests-windows / Check Run PocketIC Tests	6s
CI Main / Python CI Tests	1m 13s
CI Main / Bazel Test macOS Intel	2m 47s
CI Main / Bazel Test All	39m 2s
CI Main / Build IC	25m 5s
CI Main / Bazel Build All No Cache	0s
CI PR Only / Bazel Test Coverage	-6s
Post Required Check Status Merge Queue	-8s
CI Main / pocket-ic-tests-windows / Bazel Build PocketIC	0s
CI Main / pocket-ic-tests-windows / PocketIC Lint on Windows	0s
CI Main / pocket-ic-tests-windows / PocketIC Tests on Windows	0s
CI PR Only Post Required Check Status	9s
CI Main / Upload external artifacts	0s
CI Main / Build Determinism	4s
CI Main Required Check Status	9s
	2h 7m 59s

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