Cherry-pick #17166 to 7.7: [Filebeat] Use s3.yml as config name to match config/{{.input}}.yml in manifest.yml

[kaiyan-sheng]

Cherry-pick of PR #17166 to 7.7 branch. Original message:

This PR is to replace ec2/config/ec2.yml to ec2/config/s3.yml.

Without the change, if you run ./filebeat -e with filebeat.yml look like below:

filebeat.modules:
  - module: aws
    cloudtrail:
      enabled: true
      var.queue_url: https://sqs.us-east-1.amazonaws.com/428152502467/test-fb-ks
      var.credential_profile_name: elastic-beats
      var.visibility_timeout: 300s
      var.endpoint: amazonaws.com

output.elasticsearch:
  hosts: ["localhost:9200"]

You will get an error message:

2020-03-20T14:57:07.048-0600    ERROR   instance/beat.go:920    Exiting: Error getting config for fileset aws/ec2: Error reading input file config/s3.yml: open /Users/kaiyansheng/go/src/github.com/elastic/beats/x-pack/filebeat/module/aws/ec2/config/s3.yml: no such file or directory
Exiting: Error getting config for fileset aws/ec2: Error reading input file config/s3.yml: open /Users/kaiyansheng/go/src/github.com/elastic/beats/x-pack/filebeat/module/aws/ec2/config/s3.yml: no such file or directory

In this PR, I also replaced cloudtrail.yml and cloudwatch.yml with s3.yml so it matches config/{{.input}}.yml in manifest.yml file to be consistent with the rest of the filesets in aws.

[elasticmachine]

Pinging @elastic/integrations-platforms (Team:Platforms)

[blakerouse]

Looks good.