fix: Remove Hardcoded Bucket Name from EventBridge Example CloudFormation Template

[alanedwardes]

What this PR does / why we need it:

The current CloudFormation template for EventBridge includes a hardcoded S3 bucket name. This changes that so it uses the S3 bucket name from the input parameters.

Which issue(s) this PR fixes:
The EventBridge example template doesn't work properly without it.

Special notes for your reviewer:

Checklist

• Reviewed the CONTRIBUTING.md guide (required)
• Documentation added
• Tests updated
• Title matches the required conventional commits format, see here
• Changes that require user attention or interaction to upgrade are documented in docs/sources/setup/upgrade/_index.md
• For Helm chart changes bump the Helm chart version in production/helm/loki/Chart.yaml and update production/helm/loki/CHANGELOG.md and production/helm/loki/README.md. Example PR
• If the change is deprecating or removing a configuration option, update the deprecated-config.yaml and deleted-config.yaml files respectively in the tools/deprecated-config-checker directory. Example PR

[CLAassistant]

All committers have signed the CLA.

[MichelHollands]

lgtm