Fix Go SQLite E2E: force single connection for in-memory DB

Go's sql.DB is a connection pool. With :memory:, each connection gets
its own separate in-memory database, so INSERT on one connection is
invisible to SELECT on another. SetMaxOpenConns(1) forces all queries
to share the same in-memory database.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: SteveSandersonMS

go/internal/e2e/session_fs_sqlite_e2e_test.go

@@ -49,6 +49,8 @@ func (p *inMemorySqliteProvider) getOrCreateDBLocked() (*sql.DB, error) {
 		if err != nil {
 			return nil, err
 		}
+		// Force single connection so all queries share the same in-memory database.
+		db.SetMaxOpenConns(1)
 		_, err = db.Exec("PRAGMA busy_timeout = 5000")
 		if err != nil {
 			db.Close()