Remove one-shot migrations from Kusama Coretime (polkadot-fellows#300)

Several one-shot (single use) migrations were used in the launch of
Coretime on Kusama.
This PR removes them from the codebase since they are no longer
relevant.

I've intentionally not bumped the spec_version, since I'm not suggesting
this be released.

- [ ] Does not require a CHANGELOG entry

CHANGELOG.md

@@ -12,6 +12,10 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - Include patch to release stuck collator bonds ([polkadot-fellows/runtimes#289](https://github.com/polkadot-fellows/runtimes/pull/289))
 - Kusama chains: allow arbitrary XCM execution ([polkadot-fellows/runtimes#261](https://github.com/polkadot-fellows/runtimes/pull/261))
 
+### Removed
+
+- Remove one-shot migrations from Kusama Coretime ([polkadot-fellows/runtimes#300](https://github.com/polkadot-fellows/runtimes/pull/300))
+
 ## [1.2.3] 29.04.2024
 
 ### Added

system-parachains/coretime/coretime-kusama/src/lib.rs

@@ -23,7 +23,6 @@
 include!(concat!(env!("OUT_DIR"), "/wasm_binary.rs"));
 
 mod coretime;
-mod migrations;
 #[cfg(test)]
 mod tests;
 mod weights;
@@ -110,8 +109,6 @@ pub type UncheckedExtrinsic =
 pub type Migrations = (
 	pallet_xcm::migration::MigrateToLatestXcmVersion<Runtime>,
 	pallet_collator_selection::migration::v2::MigrationToV2<Runtime>,
-	migrations::bootstrapping::RemoveOutdatedPoolAssignment,
-	migrations::bootstrapping::OnboardPeople,
 );
 
 /// Executive: handles dispatch to the various modules.