Page size selector broken on Alerts/Events page

## Expected Behavior
When selecting a different page size, it should work.
## Current Behavior
Currently, the page size selector throws a JS error, so you cannot select a different page size.

```
vendor.8a712d83b311029bb0b6.js:672 Uncaught TypeError: o is not a function
at Events.jsx:164:5
at EventsSearchBar.jsx:66:5
at Object.s (vendor.8a712d83b311029bb0b6.js:671:467)
at m (vendor.8a712d83b311029bb0b6.js:671:617)
at W (vendor.8a712d83b311029bb0b6.js:671:675)
at D (vendor.8a712d83b311029bb0b6.js:671:862)
at g0 (vendor.8a712d83b311029bb0b6.js:672:7688)
at g1 (vendor.8a712d83b311029bb0b6.js:672:7498)
at p1 (vendor.8a712d83b311029bb0b6.js:672:7854)
at ze (vendor.8a712d83b311029bb0b6.js:672:9080)
```

## Possible Solution

## Steps to Reproduce (for bugs)
1. Got to Alerts
2. Change the page size for the table
3. Observe error in the console

## Context

## Your Environment

* Graylog Version: Graylog 5.1.0-beta.3+16b42f1
* Java Version:
* Elasticsearch Version:
* MongoDB Version:
* Operating System:
* Browser version: