Schema transaction may hang in PQ tablet

[pixcc]

1. PQ tablet sends a message to SchemeShard that the schema transaction was successfully executed
2. PQ tablet does not have time to write to disk that it has executed the transaction and restarts
3. After the restart, PQ tablet continues to execute the transaction, but it hangs because the event from the partition actor is lost.

As a result, subsequent transactions hang as well.

This is reproduced in a test with reboots that sends two consecutive transactions - creating a topic and adding a consumer to the created topic.

#14780 (comment)

With the changes from pull-request #14780, the following test falls down

./ya make -ttt --build "relwithdebinfo" -F 'TImportWithRebootsTests::ShouldSucceedOnSingleChangefeed' ydb/core/tx/schemeshard/ut_restore