Merge branch 'hotfix/21.56.4' into master

modules/live-collection-events/lib/index.js

modules/matrix-bridge/lib/constants.js

modules/matrix-bridge/lib/gitter-bridge.js

modules/matrix-bridge/lib/matrix-utils.js

modules/matrix-bridge/lib/rethrown-error.js

modules/matrix-bridge/lib/store.js

modules/matrix-bridge/test/gitter-bridge-test.js

modules/permissions/lib/policies/gh-org-policy-delegate.js

modules/permissions/lib/security-descriptor/index.js

...ions/test/security-descriptor/security-descriptor-test.js

modules/persistence-utils/lib/mongoose-utils.js

modules/persistence/lib/index.js

...ence/lib/schemas/matrix-bridged-historical-room-schema.js

modules/translations/homepage/en.json

public/templates/homepage.hbs

server/services/live-collection-handlers/index.js

...on-handlers/live-collection-group-security-descriptors.js

...ion-handlers/live-collection-room-security-descriptors.js

test/request-web-tests/matrix-bridging-power-level-tests.js