Pipe: Fix tablet event alignment and row count handling

[Caideyipi]

Description

This PR fixes two tablet event handling issues in pipe:

• Preserve the aligned flag when tablets are collected through TabletInsertionEvent.processTabletWithCollect.
• Use actual row size / row count instead of backing array capacity when checking tablet event time overlap and parsing InsertTabletNode timestamps.

This avoids treating unused timestamp slots as real rows for partially filled tablets.

Tests

• mvn -Ddevelocity.off=true spotless:apply -pl iotdb-core/datanode
• mvn -Ddevelocity.off=true -pl iotdb-core/datanode -am -Dtest=PipeTabletInsertionEventTest#processAlignedTabletWithCollectPreservesAlignmentForTest+isEventTimeOverlappedWithTimeRangeUsesActualRowSizeForTest+isEventTimeOverlappedWithTimeRangeTest -DfailIfNoTests=false -Dsurefire.failIfNoSpecifiedTests=false test
• git diff --check