distsqlrun: fix panic due to multiple calls to tracing.FinishSpan

This commit removes calls to tracing.FinishSpan from the samplerProcessor
and sampleAggregatorProcessor. These calls are no longer necessary after
memory accounting was added in #39144, which includes a call to
tracing.FinishSpan in InternalClose().

Fixes #39262

Release note: None

Author: rytaft

pkg/sql/distsqlrun/sample_aggregator.go

@@ -135,7 +135,6 @@ func (s *sampleAggregator) pushTrailingMeta(ctx context.Context) {
 func (s *sampleAggregator) Run(ctx context.Context) {
 	s.input.Start(ctx)
 	s.StartInternal(ctx, sampleAggregatorProcName)
-	defer tracing.FinishSpan(s.span)
 
 	earlyExit, err := s.mainLoop(s.Ctx)
 	if err != nil {

pkg/sql/distsqlrun/sampler.go

@@ -26,7 +26,6 @@ import (
 	"github.com/cockroachdb/cockroach/pkg/util/mon"
 	"github.com/cockroachdb/cockroach/pkg/util/randutil"
 	"github.com/cockroachdb/cockroach/pkg/util/timeutil"
-	"github.com/cockroachdb/cockroach/pkg/util/tracing"
 	"github.com/cockroachdb/errors"
 )
 
@@ -172,7 +171,6 @@ func (s *samplerProcessor) pushTrailingMeta(ctx context.Context) {
 func (s *samplerProcessor) Run(ctx context.Context) {
 	s.input.Start(ctx)
 	s.StartInternal(ctx, samplerProcName)
-	defer tracing.FinishSpan(s.span)
 
 	earlyExit, err := s.mainLoop(s.Ctx)
 	if err != nil {