Fixes for migrations tests

[bashtanov]

Tests/migrations: relax migrations tests: do not check for number of migrations when using high level API under failure injector.
Eventual consistency of migrations table may come late, and we'd rather not wait for it to test but move on with other actions to see how a disturbed cluster copes with active use.

Raft/consensus: catch ss::condition_variable_timed_out not ss::timed_out_error when waiting for a condvar with timeout. Otherwise it bubbles up unhandled appearing in logs and potentially breaking the logic too.

Tests/migrations: run mount/unmount commands without finjector. Otherwise we'd need to be prepared to a situation where we get no successful reply from admin API, but the migration is nevertheless created (node killed right before it has sent a reply). When testing low level API we handle this by checking the migration is present. But high-level mount/unmount commands auto-remove migration objects on completion. Telling apart an uncreated and a completed migration in the test logic would be somewhat tricky.

Backports Required

• none - not a bug fix
• none - this is a backport
• none - issue does not exist in previous branches
• none - papercut/not impactful enough to backport
• v24.2.x
• v24.1.x
• v23.3.x

Release Notes

• none

[bashtanov]

bazel build failure is https://redpandadata.atlassian.net/issues/CORE-8112

[vbotbuildovich]

the below tests from https://buildkite.com/redpanda/redpanda/builds/57834#01930b9c-fc4b-4f48-a4b4-68e8ca969689 have failed and will be retried

translator_test_rpfixture

[bashtanov]

this one is also known https://redpandadata.atlassian.net/issues/CORE-8093

[vbotbuildovich]

ducktape was retried in https://buildkite.com/redpanda/redpanda/builds/57834#01930bde-74c5-4508-b4bb-f3ce79768742
ducktape was retried in https://buildkite.com/redpanda/redpanda/builds/57834#01930bf9-31a7-4c2d-8f0a-be0e22a0e481
ducktape was retried in https://buildkite.com/redpanda/redpanda/builds/57854#01930d2b-9fd6-4ede-969e-58e657a823f7
ducktape was retried in https://buildkite.com/redpanda/redpanda/builds/57854#01930d2b-9fd3-4bab-9a37-474454a9f917

[vbotbuildovich]

Retry command for Build#57834

please wait until all jobs are finished before running the slash command

/ci-repeat 1
tests/rptest/tests/data_migrations_api_test.py::DataMigrationsApiTest.test_creating_and_listing_migrations
tests/rptest/tests/data_migrations_api_test.py::DataMigrationsApiTest.test_higher_level_migration_api

[vbotbuildovich]

non flaky failures in https://buildkite.com/redpanda/redpanda/builds/57834#01930bf9-31a1-44ca-85c9-373157f3f2a0:

"rptest.tests.data_migrations_api_test.DataMigrationsApiTest.test_higher_level_migration_api"

[dotnwat]

too bad they didn't inherit from timed_out_error :/