Not list all environments
When a have more than 50 environments the /environments endpoint only returns 50 items because DEFAULT_PAGE_SIZE=50.
This affects when I need to create a blackout, then I can`t get it all.

Environment

• OS: [Linux]

• API version: [eg. 6.8.1]

• Deployment: [ self-hosted]

• Database: [ Postgres]

• Server config:
  Auth enabled? Yes
  Auth provider? LDAP, etc
  Customer views? No
  (or provide the /config endpoint output)

• CLI version: [eg. 8.5.0]

To Reproduce
Steps to reproduce the behavior:

1. Create more than 50 alerts with different environment
2. Consume /environments endpoint
3. See error (Only return the first 50 items)