fix: add cancel case to isStreaming state

mentioned in commit bf12ba63

mentioned in merge request status-page!903

mentioned in merge request gitlab-org/frontend/pajamas-adoption-scanner!338 (merged)

mentioned in merge request gitlab!160452 (merged)

mentioned in merge request gitlab-org/frontend/playground/accessibility-scanner!45 (merged)

mentioned in merge request gitlab-org/frontend/playground/accessibility-scanner!46 (closed)

mentioned in merge request gitlab-org/gitlab-services/design.gitlab.com!3986 (merged)

mentioned in merge request gitlab-org/editor-extensions/gitlab-jetbrains-plugin!783 (closed)

mentioned in merge request gitlab-org/editor-extensions/gitlab-jetbrains-plugin!811 (closed)