vecindex: remove Begin/Commit/Abort Transaction methods

Remove the BeginTransaction, CommitTransaction, and AbortTransaction methods
from the cspann.Store interface. These methods are superseded by the
RunTransaction method. Fix up all test usages of any of these methods to
use a new commontest.RunTransaction helper function.

Epic: CRDB-42943

Release note: None

Author: andy-kimball

pkg/cmd/vecbench/mem_provider.go

@@ -128,34 +128,27 @@ func (m *MemProvider) InsertVectors(
 func (m *MemProvider) Search(
 	ctx context.Context, vec vector.T, maxResults int, beamSize int, stats *cspann.SearchStats,
 ) (keys []cspann.KeyBytes, err error) {
-	var txn cspann.Txn
-	txn, err = m.store.BeginTransaction(ctx)
-	defer func() {
-		if err == nil {
-			err = m.store.CommitTransaction(ctx, txn)
-		}
+	err = m.store.RunTransaction(ctx, func(txn cspann.Txn) error {
+		// Search the store.
+		var idxCtx cspann.Context
+		idxCtx.Init(txn)
+		searchSet := cspann.SearchSet{MaxResults: maxResults}
+		searchOptions := cspann.SearchOptions{BaseBeamSize: beamSize}
+		err = m.index.Search(ctx, &idxCtx, nil /* treeKey */, vec, &searchSet, searchOptions)
 		if err != nil {
-			err = m.store.AbortTransaction(ctx, txn)
+			return err
 		}
-	}()
-
-	// Search the store.
-	var idxCtx cspann.Context
-	idxCtx.Init(txn)
-	searchSet := cspann.SearchSet{MaxResults: maxResults}
-	searchOptions := cspann.SearchOptions{BaseBeamSize: beamSize}
-	err = m.index.Search(ctx, &idxCtx, nil /* treeKey */, vec, &searchSet, searchOptions)
-	if err != nil {
-		return nil, err
-	}
-	*stats = searchSet.Stats
+		*stats = searchSet.Stats
 
-	// Get result keys.
-	results := searchSet.PopResults()
-	keys = make([]cspann.KeyBytes, len(results))
-	for i, res := range results {
-		keys[i] = []byte(res.ChildKey.KeyBytes)
-	}
+		// Get result keys.
+		results := searchSet.PopResults()
+		keys = make([]cspann.KeyBytes, len(results))
+		for i, res := range results {
+			keys[i] = []byte(res.ChildKey.KeyBytes)
+		}
+
+		return nil
+	})
 
 	return keys, err
 }