fix(vm-runner): change processing_started_at column type to `timest…

…amp` (matter-labs#2397)

## What ❔



## Why ❔


## Checklist

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- [ ] PR title corresponds to the body of PR (we generate changelog
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- [ ] Tests for the changes have been added / updated.
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core/lib/dal/migrations/20240708194915_vm_runner_processing_started_at_timestamp.down.sql

@@ -0,0 +1,2 @@
+ALTER TABLE vm_runner_protective_reads ALTER COLUMN processing_started_at TYPE TIME USING (null);
+ALTER TABLE vm_runner_bwip ALTER COLUMN processing_started_at TYPE TIME USING (null);

core/lib/dal/migrations/20240708194915_vm_runner_processing_started_at_timestamp.up.sql

@@ -0,0 +1,2 @@
+ALTER TABLE vm_runner_protective_reads ALTER COLUMN processing_started_at TYPE TIMESTAMP USING (null);
+ALTER TABLE vm_runner_bwip ALTER COLUMN processing_started_at TYPE TIMESTAMP USING (null);