[Hotfix][ams] Fix ResourceMapper.selectResourcesByGroup result mapping

[lintingbin]

What changes were proposed in this pull request?

Fix the @Result annotations on ResourceMapper.selectResourcesByGroup so that the property names actually match the fields on Resource:

Column	Old property	Correct property
group_name	group	groupName
container_name	container	containerName
total_memory	totalMemory	memoryMb

Also drop the start_time column from the SELECT list and remove its @Result entry. Resource has no startTime field, so the mapping was silently discarded — keeping the column in the projection added no value.

Why are the changes needed?

These mapping names have never matched the target class. Currently DefaultOptimizerManager.listResourcesByGroup is the only path that calls this mapper, and it has no caller on master, so the bug was latent. Any future caller (e.g. the auto-restart optimizer feature under development) that starts using this method would get back Resource instances with null/0 values in groupName, containerName, and memoryMb. Fixing it as a standalone change keeps the diff minimal and makes it safe to cherry-pick.

Does this PR introduce any user-facing change?

No.

How was this patch tested?

• Verified no current caller of selectResourcesByGroup / listResourcesByGroup exists on master besides the declaration itself, so the change cannot regress existing behavior.
• mvn spotless:apply passes.

[zhoujinsong]

The fix is correct and minimal.

All three @Result property names now match the actual fields on Resource (groupName, containerName, memoryMb), and the stale start_time mapping is correctly removed since Resource has no startTime field.

One minor note for future reference: the start_time column still exists in the DB schema (populated by DEFAULT CURRENT_TIMESTAMP) but has no corresponding field in Resource — this is intentional and the exclusion from result mapping is correct. Worth keeping in mind if the schema is ever revisited.

LGTM.