Export Partition - release the part lock when the query is cancelled

[arthurpassos]

During export partition, parts are locked by replicas for exports. This PR introduces a change that releases these locks when an export task is cancelled. Previously, it would not release the lock. We did not catch this error before because the only cases an export task was cancelled we tested were KILL EXPORT PARTITION and DROP TABLE. In those cases, the entire task is cancelled, so it does not matter if a replica does not release its lock.

But a query can also be cancelled with 'SYSTEM STOP MOVES', and in that case, it is a local operation. The lock must be released so other replicas can continue.

Changelog category (leave one):

• Bug Fix (user-visible misbehavior in an official stable release)

Changelog entry (a user-readable short description of the changes that goes to CHANGELOG.md):

1. During an export partition operation, release the part lock in case the export task has been cancelled.
2. Do not run the scheduler if moves are stopped

Documentation entry for user-facing changes

...

CI/CD Options

Exclude tests:

• Fast test
• Integration Tests
• Stateless tests
• Stateful tests
• Performance tests
• All with ASAN
• All with TSAN
• All with MSAN
• All with UBSAN
• All with Coverage
• All with Aarch64
• All Regression
• Disable CI Cache

Regression jobs to run:

• Fast suites (mostly <1h)
• Aggregate Functions (2h)
• Alter (1.5h)
• Benchmark (30m)
• ClickHouse Keeper (1h)
• Iceberg (2h)
• LDAP (1h)
• Parquet (1.5h)
• RBAC (1.5h)
• SSL Server (1h)
• S3 (2h)
• S3 Export (2h)
• Swarms (30m)
• Tiered Storage (2h)

[github-actions]

Workflow [PR], commit [a858334]

[arthurpassos]

@codex review