cmd/geth: fix failing test (#28322)

cmd/geth/genesis_test.go

@@ -176,12 +176,12 @@ func TestCustomBackend(t *testing.T) {
 		{ // Can't start pebble on top of leveldb
 			initArgs:   []string{"--db.engine", "leveldb"},
 			execArgs:   []string{"--db.engine", "pebble"},
-			execExpect: `Fatal: Could not open database: db.engine choice was pebble but found pre-existing leveldb database in specified data directory`,
+			execExpect: `Fatal: Failed to register the Ethereum service: db.engine choice was pebble but found pre-existing leveldb database in specified data directory`,
 		},
 		{ // Can't start leveldb on top of pebble
 			initArgs:   []string{"--db.engine", "pebble"},
 			execArgs:   []string{"--db.engine", "leveldb"},
-			execExpect: `Fatal: Could not open database: db.engine choice was leveldb but found pre-existing pebble database in specified data directory`,
+			execExpect: `Fatal: Failed to register the Ethereum service: db.engine choice was leveldb but found pre-existing pebble database in specified data directory`,
 		},
 		{ // Reject invalid backend choice
 			initArgs:   []string{"--db.engine", "mssql"},