Remove FsTokenPersistence (#5671)

config/custom-environment-variables.yml

config/default.yml

core/server/server.js

core/token-pooling/fs-token-persistence.js

core/token-pooling/fs-token-persistence.spec.js

core/token-pooling/redis-token-persistence.js

core/token-pooling/token-persistence.js

package-lock.json

package.json

scripts/redis-connectivity-test.js

services/github/github-constellation.js