[SPARK-46484][SQL][CONNECT] Retain plan_id in resolveOperators

[zhengruifeng]

What changes were proposed in this pull request?

Retain plan_id in resolveOperators

Why are the changes needed?

another attempt to fix #44454

Does this PR introduce any user-facing change?

no

How was this patch tested?

added ut

Was this patch authored or co-authored using generative AI tooling?

no

[zhengruifeng]

this is the previous approach to fix missing plan_id issue:
1, figure out what rules drop the plan_id tag;
2, use copyTagsFrom to copy the tag from old plan to new plan;

Both UnpivotCoercion and ResolveUnpivot leverage resolveOperatorsDownWithPruning, so I'm trying to fix it by making resolveOperatorsDownWithPruning keep the plan_id tag;

cc @cloud-fan @HyukjinKwon

[zhengruifeng]

close in favor of #44462